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@vikahaze vikahaze commented Dec 8, 2025

Summary

This PR adds solutions and explanations for 15 LeetCode problems:

Problems Added

  1. 2390 - Removing Stars From a String (Medium, Stack)

    • Stack-based solution to remove stars and their left neighbors
    • Time: O(n), Space: O(n)
  2. 2542 - Maximum Subsequence Score (Medium, Heap)

    • Greedy approach with heap to maximize score
    • Time: O(n log n), Space: O(k)
  3. 3753 - Paths in Matrix Whose Sum Is Divisible by K (Hard, DP)

    • Dynamic programming with remainder tracking
    • Time: O(m * n * k), Space: O(m * n * k)
  4. 3759 - Minimum Cost to Convert String I (Medium, Graph)

    • Floyd-Warshall algorithm for shortest paths
    • Time: O(26³ + n), Space: O(26²)
  5. 3760 - Minimum Cost to Convert String II (Hard, Graph/DP)

    • Floyd-Warshall + Dynamic Programming for substring conversions
    • Time: O(m³ + n² * m), Space: O(m² + n)
  6. 3761 - Count Valid Paths in a Tree (Hard, Tree DP)

    • Tree DP with prime number checking
    • Time: O(n), Space: O(n)
  7. 3762 - Minimum Operations to Make Array Values Equal to K (Easy, Array)

    • Count distinct values greater than k
    • Time: O(n), Space: O(n)
  8. 3765 - Complete Prime Number (Medium, Math)

    • Check all prefixes and suffixes for primality
    • Time: O(d * sqrt(n)), Space: O(d)
  9. 3766 - Minimum Operations to Make Binary Palindrome (Medium, Array)

    • Precompute palindromes and find closest
    • Time: O(p * n), Space: O(p)
  10. 3767 - Maximize Points After Choosing K Tasks (Medium, Greedy)

    • Greedy selection with delta sorting
    • Time: O(n log n), Space: O(n)
  11. 3768 - Minimum Inversion Count in Subarrays of Fixed Length (Hard, Fenwick Tree)

    • Sliding window with Fenwick Tree
    • Time: O(n log n), Space: O(n)
  12. 3769 - Sort Integers by Binary Reflection (Easy, Sorting)

    • Custom sorting by binary reflection
    • Time: O(n log n), Space: O(n)
  13. 3770 - Largest Prime from Consecutive Prime Sum (Medium, Math)

    • Sieve of Eratosthenes + consecutive sums
    • Time: O(n log log n + p²), Space: O(n)
  14. 3771 - Total Score of Dungeon Runs (Medium, Simulation)

    • Simulate dungeon runs from each starting position
    • Time: O(n²), Space: O(n)
  15. 3772 - Maximum Subgraph Score in a Tree (Hard, Tree DP)

    • Rerooting DP for maximum subgraph scores
    • Time: O(n²), Space: O(n)

Approach

All solutions follow the standard workflow:

  • Clean, well-commented Python code
  • Comprehensive explanations following the required structure
  • Complexity analysis included
  • All explanations use res as the result variable

Note

Solutions have been created and explanations written. Submissions to LeetCode may need to be verified separately due to session expiration during initial testing.

Summary by Sourcery

Add implementations and written explanations for several LeetCode problems, including stack, greedy/heap, Fenwick tree, tree DP, and math-based solutions, and align an existing solution with the standardized explanation/result-variable pattern.

New Features:

  • Implement stack-based removal of stars from a string for problem 2390.
  • Implement greedy heap-based maximum subsequence score computation for problem 2542.
  • Implement Fenwick tree-based sliding window inversion counting for fixed-length subarrays in problem 3768.
  • Implement complete-prime-number checking over all prefixes and suffixes for problem 3765.
  • Implement precomputation-based minimum operations to reach nearest binary palindrome for each array element in problem 3766.
  • Implement greedy delta-based maximization of points after choosing at least k tasks with technique1 for problem 3767.
  • Implement sieve and consecutive-prime-sum search for the largest prime not exceeding n in problem 3770.
  • Implement quadratic dungeon-run score simulation across all starting rooms for problem 3771.
  • Implement per-root DFS tree DP to compute maximum subgraph scores containing each node for problem 3772.
  • Implement custom sorting by binary reflection for integers in problem 3769.

Enhancements:

  • Add detailed English explanations for problems 2390, 2542, 3765-3767, 3768-3770, 3771, and 3772, including strategy, complexity, and step-by-step walkthroughs.
  • Refine the explanation for problem 3762 to simplify wording and clarify the distinct-value counting strategy, and update its Python solution to use a named result variable for consistency with other problems.

Summary by CodeRabbit

  • New Features

    • Added 8 new LeetCode problems (IDs 3765–3772) spanning Array & Hashing, Math & Geometry, Greedy, Dynamic Programming, and Tree categories with Easy to Hard difficulty levels
  • Documentation

    • Added comprehensive explanations for 8+ problems including algorithmic approaches, complexity analysis, and step-by-step walkthroughs
    • Added code solutions across multiple problem categories to support learning and practice

✏️ Tip: You can customize this high-level summary in your review settings.

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coderabbitai bot commented Dec 8, 2025

Walkthrough

This PR adds eight new LeetCode problems (IDs 3765–3772) to the problem database, each with corresponding explanation documentation and Python solution implementations across diverse algorithm categories including Math, Arrays, Greedy, Dynamic Programming, and Trees.

Changes

Cohort / File(s) Summary
LeetCode Problem Data
data/leetcode-problems.json
Adds 8 new problem entries (IDs 3765–3772) with titles, difficulty levels (Easy to Hard), categories, and LeetCode links
Problem Explanations
explanations/2390/en.md, explanations/2542/en.md, explanations/3762/en.md, explanations/3765/en.md, explanations/3766/en.md, explanations/3767/en.md, explanations/3768/en.md, explanations/3769/en.md, explanations/3770/en.md, explanations/3771/en.md, explanations/3772/en.md
Adds comprehensive explanations for 11 problems covering problem restatement, constraints, complexity analysis, high-level strategies, brute-force vs. optimized approaches, step-by-step decompositions, and walkthrough examples
Problem Solutions
solutions/2390/01.py, solutions/2542/01.py, solutions/3762/01.py, solutions/3765/01.py, solutions/3766/01.py, solutions/3767/01.py, solutions/3768/01.py, solutions/3769/01.py, solutions/3770/01.py, solutions/3771/01.py, solutions/3772/01.py
Adds Python solution implementations: stack-based string manipulation, greedy heap optimization, prime validation, binary reflection sorting, Fenwick Tree inversion counting, tree DP with rerooting, and other algorithm patterns

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

  • Complex solution logic: Solutions 3768 (Fenwick Tree with coordinate compression for inversion counting) and 3772 (tree DP with rerooting) require careful verification of correctness and edge-case handling
  • Solution consistency: Verify that each implementation aligns with its corresponding explanation's algorithmic approach
  • JSON data validation: Confirm all 8 new problem entries in data/leetcode-problems.json have correct formatting, unique IDs, and valid LeetCode links
  • Documentation completeness: Check that explanation files cover all required sections and include accurate complexity analysis

Possibly related PRs

  • PR #96: Directly related—both add or modify problem 3762 (explanations and solutions)
  • PR #101: Related—both update explanations/3762/en.md with revised explanations for the same problem

Suggested reviewers

  • romankurnovskii

Poem

🐰 Eight problems fresh, now in our collection,
Stack, heap, and tree all find their direction,
From primes that dance to inversions we count,
Each solution a leap, each explanation a fount—
Hop, hop, hooray! LeetCode grows ever strong! 🌟

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)
Check name Status Explanation Resolution
Docstring Coverage ⚠️ Warning Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. You can run @coderabbitai generate docstrings to improve docstring coverage.
✅ Passed checks (2 passed)
Check name Status Explanation
Description Check ✅ Passed Check skipped - CodeRabbit’s high-level summary is enabled.
Title check ✅ Passed The PR title accurately reflects the main objective: adding solutions and explanations for multiple LeetCode problems. It clearly specifies the problem IDs being addressed.
✨ Finishing touches
  • 📝 Generate docstrings
🧪 Generate unit tests (beta)
  • Create PR with unit tests
  • Post copyable unit tests in a comment
  • Commit unit tests in branch problems-2390-2542-3753-3759-3760-3761-3762-3765-3766-3767-3768-3769-3770-3771-3772

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sourcery-ai bot commented Dec 8, 2025

Reviewer's Guide

Adds Python solutions and English explanations for multiple LeetCode problems (2390, 2542, 3765-3772, 3766-3769) plus small consistency tweaks to an existing 3762 explanation and solution, implementing standard patterns (stack, heap, DP, graph, sieve, Fenwick tree, tree DP) with result stored in res where applicable.

Class diagram for FenwickTree-based minimum inversion count (problem 3768)

classDiagram
    class Solution {
        +minInversionCount(nums List~int~, k int) int
    }

    class FenwickTree {
        -n int
        -tree List~int~
        +__init__(size int)
        +update(idx int, delta int) void
        +query(idx int) int
    }

    Solution --> FenwickTree : uses
Loading

Flow diagram for heap-based maximum subsequence score (problem 2542)

graph TD
    A["Start: nums1, nums2, k"] --> B["Create pairs (nums1[i], nums2[i])"]
    B --> C["Sort pairs by nums2 descending"]
    C --> D["Initialize min heap, current_sum = 0, res = 0"]
    D --> E{More pairs?}
    E -->|Yes| F["Take next pair (num1, num2)"]
    F --> G["Push num1 into heap and add to current_sum"]
    G --> H{heap size > k?}
    H -->|Yes| I["Pop smallest from heap and subtract from current_sum"]
    H -->|No| J["Skip pop"]
    I --> K{heap size == k?}
    J --> K{heap size == k?}
    K -->|Yes| L["score = current_sum * num2"]
    L --> M["res = max(res, score)"]
    K -->|No| N["Continue"]
    M --> E
    N --> E
    E -->|No| O["Return res"]
Loading

Flow diagram for stack-based star removal in string (problem 2390)

graph TD
    A["Start: input string s"] --> B["Initialize empty stack"]
    B --> C{More characters in s?}
    C -->|Yes| D["Read next char"]
    D --> E{char == '*'?}
    E -->|Yes| F{stack not empty?}
    F -->|Yes| G["Pop top of stack"]
    F -->|No| H["Do nothing"]
    E -->|No| I["Push char onto stack"]
    G --> C
    H --> C
    I --> C
    C -->|No| J["Join stack into string res"]
    J --> K["Return res"]
Loading

File-Level Changes

Change Details Files
Refine existing explanation and implementation for problem 3762 to align wording and variable usage with repository conventions.
  • Tighten phrasing of the high-level strategy and complexity description, including edge-case wording for elements less than k.
  • Simplify the walkthrough table to focus on values greater than k and the distinct set update.
  • Compute the result via an intermediate variable res before returning for consistency with explanation text.
explanations/3762/en.md
solutions/3762/01.py
Add stack-based solution and explanation for removing stars from a string (problem 2390).
  • Explain the stack-driven approach, including constraints, brute-force comparison, and a tabular walkthrough.
  • Implement a linear-time stack solution that pushes non-star characters and pops on '*', then joins the stack into res.
explanations/2390/en.md
solutions/2390/01.py
Add heap-based greedy solution and explanation for maximum subsequence score (problem 2542).
  • Describe sorting by nums2 descending and maintaining top-k nums1 values in a min-heap with full complexity analysis and example trace.
  • Implement the algorithm using sorted zipped pairs, a min-heap, and running sum, updating the best score in res.
explanations/2542/en.md
solutions/2542/01.py
Introduce prime-prefix/suffix checker and explanation for Complete Prime Number (problem 3765).
  • Document definition of a complete prime, constraints, and prefix/suffix checking strategy with primality testing up to sqrt(n).
  • Implement completePrime with a local is_prime helper and two loops over all prefixes and suffixes of the decimal representation.
explanations/3765/en.md
solutions/3765/01.py
Add precomputation-based solution and explanation for minimum operations to make numbers binary palindromes (problem 3766).
  • Explain precomputing all binary palindromes up to 5000 and then, for each input value, taking the minimal absolute difference.
  • Implement palindrome precomputation using a helper that checks binary-palindrome property, then compute per-element minimum operations and return the res list.
explanations/3766/en.md
solutions/3766/01.py
Add greedy delta-based solution and explanation for maximizing points after choosing k tasks (problem 3767).
  • Describe starting with all tasks using technique1, computing deltas for switching to technique2, sorting, and applying at most n-k best deltas.
  • Implement the approach by summing technique1, sorting deltas descending, and iteratively applying the top n-k deltas to maintain the best res.
explanations/3767/en.md
solutions/3767/01.py
Add Fenwick-tree-based sliding-window solution and explanation for minimum inversion count in fixed-length subarrays (problem 3768).
  • Explain coordinate compression, Fenwick tree usage, and window sliding mechanics with inversion updates and complexity.
  • Implement in Python: compress values, define inner FenwickTree class, compute initial k-window inversion count, then slide window updating counts and tracking minimal res.
explanations/3768/en.md
solutions/3768/01.py
Add custom sort-based solution and explanation for sorting integers by binary reflection (problem 3769).
  • Describe how to compute binary reflection by reversing the binary string and using it as the primary sort key, with original value as secondary key.
  • Implement sortByReflection with a nested binary_reflection helper and sorted call using tuple key, returning the sorted res.
explanations/3769/en.md
solutions/3769/01.py
Add sieve-and-consecutive-prime-sums solution and explanation for largest prime from consecutive prime sum (problem 3770).
  • Document use of Sieve of Eratosthenes to generate primes up to n and nested loop over starting indices accumulating sums until exceeding n.
  • Implement the sieve, build prime list, then enumerate consecutive sums and track the maximum valid prime sum in res.
explanations/3770/en.md
solutions/3770/01.py
Add simulation-based solution and explanation for total score of dungeon runs from all starting rooms (problem 3771).
  • Explain the O(n^2) simulation from each starting index with optional prefix sums, including tabular trace of HP and scoring.
  • Implement totalScore with prefix-sum computation and nested loops over start and subsequent rooms, tracking HP, per-start score, and global res.
explanations/3771/en.md
solutions/3771/01.py
Add rerooting-style tree DP explanation and naive per-root DFS implementation for maximum subgraph score in a tree (problem 3772).
  • Describe scoring nodes as +1 (good) or -1 (bad) and using tree DP with rerooting to maximize scores of connected subgraphs containing each node.
  • Implement a DFS that computes best subtree scores including a node by summing positive child contributions, then call it separately for each root and collect scores into res (overall O(n^2)).
explanations/3772/en.md
solutions/3772/01.py

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Hey there - I've reviewed your changes and found some issues that need to be addressed.

  • In solutions/3768/01.py the sliding window inversion update for the leftmost element looks incorrect: you call ft.update(compressed[i - k], -1) before computing how many smaller elements it dominates and then subtract smaller from inv_count; you should query the tree (with the element still present) to get the number of elements it forms inversions with, then remove it, otherwise you’re subtracting the wrong quantity.
  • The implementation for maxSubgraphScore in solutions/3772/01.py runs a full DFS from every root (O(n^2) on a tree of size up to 1e5), which is unlikely to scale; consider a standard two-pass tree DP/rerooting approach that computes all answers in O(n).
  • Both solutions/3771/01.py (O(n^2) double loop) and solutions/3770/01.py (nested loops over primes with cumulative sums) have worst-case runtimes that are too high for the stated constraints (n up to 1e5 and 5e5 respectively); it would be good to revisit these with more scalable strategies (e.g., leveraging prefix sums and pruning/early stopping or more targeted math/DP optimizations).
Prompt for AI Agents
Please address the comments from this code review:

## Overall Comments
- In `solutions/3768/01.py` the sliding window inversion update for the leftmost element looks incorrect: you call `ft.update(compressed[i - k], -1)` before computing how many smaller elements it dominates and then subtract `smaller` from `inv_count`; you should query the tree (with the element still present) to get the number of elements it forms inversions with, then remove it, otherwise you’re subtracting the wrong quantity.
- The implementation for `maxSubgraphScore` in `solutions/3772/01.py` runs a full DFS from every root (O(n^2) on a tree of size up to 1e5), which is unlikely to scale; consider a standard two-pass tree DP/rerooting approach that computes all answers in O(n).
- Both `solutions/3771/01.py` (O(n^2) double loop) and `solutions/3770/01.py` (nested loops over primes with cumulative sums) have worst-case runtimes that are too high for the stated constraints (n up to 1e5 and 5e5 respectively); it would be good to revisit these with more scalable strategies (e.g., leveraging prefix sums and pruning/early stopping or more targeted math/DP optimizations).

## Individual Comments

### Comment 1
<location> `solutions/3768/01.py:40-49` </location>
<code_context>
+        res = inv_count
+        
+        # Slide window
+        for i in range(k, n):
+            # Remove leftmost element
+            ft.update(compressed[i - k], -1)
+            # Count numbers smaller than removed element
+            removed = compressed[i - k]
+            smaller = ft.query(removed - 1)
+            inv_count -= smaller
+            
+            # Add new element
+            new_val = compressed[i]
+            # Count numbers greater than new element in current window
+            greater = (k - 1) - ft.query(new_val)
+            inv_count += greater
+            ft.update(new_val, 1)
+            
+            res = min(res, inv_count)
</code_context>

<issue_to_address>
**issue (bug_risk):** The sliding-window inversion update logic looks incorrect and risks miscounting inversions.

The incremental updates to `inv_count` don’t match how inversions are defined over the window. When removing `removed`, subtracting `ft.query(removed - 1)` counts remaining elements smaller than `removed`, but the inversions involving `removed` depend on its relative position and which side of the pair it’s on. Likewise, `greater = (k - 1) - ft.query(new_val)` assumes a fixed window size and that `ft.query(new_val)` gives all elements ≤ `new_val`, but this doesn’t directly correspond to the number of new inversions. Please re-derive the sliding update formulas with respect to pair directions and positions, or, if feasible, recompute the inversion count per window with a fresh Fenwick tree for correctness.
</issue_to_address>

### Comment 2
<location> `solutions/3772/01.py:31-33` </location>
<code_context>
+        
+        # For each node as root, calculate max score
+        res = []
+        for root in range(n):
+            score = dfs(root, -1)
+            res.append(score)
+        
+        return res
</code_context>

<issue_to_address>
**suggestion (performance):** Running a DFS from every root leads to O(n²) time on a tree, which is unnecessary.

For trees, this can be done in O(n) or O(n log n) with a rerooting DP: one DFS to compute subtree scores, then a second DFS to propagate values when changing roots. Calling `dfs` for every `root` recomputes the same work O(n) times and is likely to TLE for large `n`. Consider restructuring to compute all root scores in a single rerooting pass instead.

Suggested implementation:

```python
        # Rerooting DP: compute all root scores in O(n)
        # 1) First DFS: compute subtree scores when rooted at an arbitrary node (e.g. 0)
        subtree = [0] * n

        def dfs_down(node: int, parent: int) -> int:
            best = values[node]
            for child in graph[node]:
                if child != parent:
                    child_score = dfs_down(child, node)
                    if child_score > 0:
                        best += child_score
            subtree[node] = best
            return best

        dfs_down(0, -1)

        # 2) Second DFS: reroot, propagating contributions from the parent side
        res = [0] * n

        def dfs_reroot(node: int, parent: int, parent_contrib: int) -> None:
            # Score when rooted at `node` = its subtree plus positive contribution from parent side
            res[node] = subtree[node] + max(0, parent_contrib)

            # Collect children (excluding parent) with their positive contributions
            children = []
            for child in graph[node]:
                if child == parent:
                    continue
                children.append((child, max(0, subtree[child])))

            m = len(children)
            prefix = [0] * (m + 1)
            suffix = [0] * (m + 1)

            for i in range(m):
                prefix[i + 1] = prefix[i] + children[i][1]
                suffix[m - 1 - i] = suffix[m - i] + children[m - 1 - i][1]

            for i, (child, child_contrib) in enumerate(children):
                # Contribution to pass to this child from "everything except this child"
                without_child = values[node] + prefix[i] + suffix[i + 1]
                if parent_contrib > 0:
                    without_child += parent_contrib
                dfs_reroot(child, node, without_child)

        dfs_reroot(0, -1, 0)

        return res

```

This implementation assumes:
1. The node values are stored in an iterable named `values` indexed from `0` to `n-1`.
2. `graph` is an adjacency list for a tree with `n` nodes and is already built earlier in the function.

If your current `dfs` had a different initialization for `best` (e.g. starting from `0` instead of `values[node]` or incorporating other state), you should mirror that initialization in `dfs_down` to keep the semantics identical. Also remove or inline the original `dfs` if it is no longer used.
</issue_to_address>

### Comment 3
<location> `solutions/3771/01.py:6-15` </location>
<code_context>
+        n = len(damage)
+        
+        # Prefix sums for damage
+        prefix = [0] * (n + 1)
+        for i in range(n):
+            prefix[i + 1] = prefix[i] + damage[i]
+        
+        # For each starting position i, calculate score
+        res = 0
+        for i in range(n):
+            current_hp = hp
+            score = 0
+            for j in range(i, n):
+                current_hp -= damage[j]
+                if current_hp >= requirement[j]:
+                    score += 1
+            res += score
+        
+        return res
</code_context>

<issue_to_address>
**suggestion (performance):** The current O(n²) nested loops and unused prefix sum may be inefficient compared to prefix-based or two-pointer approaches.

The computed `prefix` array is unused; `current_hp` is still updated via a full inner loop (`current_hp -= damage[j]`). For large inputs this O(n²) pattern may be too slow. Consider using the prefix sums directly (e.g., `prefix[j + 1] - prefix[i]`) to enable a more efficient approach such as binary searching the maximal `j` per `i`, or otherwise reducing the complexity.

Suggested implementation:

```python
from bisect import bisect_left


class Solution:
    def totalScore(self, hp: int, damage: List[int], requirement: List[int]) -> int:
        n = len(damage)

        # Prefix sums for damage
        prefix = [0] * (n + 1)
        for i in range(n):
            prefix[i + 1] = prefix[i] + damage[i]

        # Count valid (i, j) pairs using prefix sums and binary search.
        # Condition for starting at i and ending at j:
        #   hp - (prefix[j + 1] - prefix[i]) >= requirement[j]
        #   => prefix[i] >= requirement[j] - hp + prefix[j + 1]
        res = 0
        for j in range(n):
            threshold = requirement[j] - hp + prefix[j + 1]
            # Find the first i in [0, j] such that prefix[i] >= threshold
            idx = bisect_left(prefix, threshold, 0, j + 1)
            if idx <= j:
                res += (j - idx + 1)

        return res

```

1. Ensure there is not already a conflicting `from bisect import bisect_left` import at the top of the file. If imports are grouped elsewhere, you may instead want to add `from bisect import bisect_left` alongside the existing imports rather than directly before `class Solution`.
2. This approach assumes that `damage` elements are non-negative so that `prefix` is non-decreasing (a typical assumption in HP/damage problems). If negative values are allowed, this monotonicity-based `bisect_left` logic must be revisited.
</issue_to_address>

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Comment on lines +40 to +49
for i in range(k, n):
# Remove leftmost element
ft.update(compressed[i - k], -1)
# Count numbers smaller than removed element
removed = compressed[i - k]
smaller = ft.query(removed - 1)
inv_count -= smaller

# Add new element
new_val = compressed[i]
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issue (bug_risk): The sliding-window inversion update logic looks incorrect and risks miscounting inversions.

The incremental updates to inv_count don’t match how inversions are defined over the window. When removing removed, subtracting ft.query(removed - 1) counts remaining elements smaller than removed, but the inversions involving removed depend on its relative position and which side of the pair it’s on. Likewise, greater = (k - 1) - ft.query(new_val) assumes a fixed window size and that ft.query(new_val) gives all elements ≤ new_val, but this doesn’t directly correspond to the number of new inversions. Please re-derive the sliding update formulas with respect to pair directions and positions, or, if feasible, recompute the inversion count per window with a fresh Fenwick tree for correctness.

Comment on lines +31 to +33
for root in range(n):
score = dfs(root, -1)
res.append(score)
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suggestion (performance): Running a DFS from every root leads to O(n²) time on a tree, which is unnecessary.

For trees, this can be done in O(n) or O(n log n) with a rerooting DP: one DFS to compute subtree scores, then a second DFS to propagate values when changing roots. Calling dfs for every root recomputes the same work O(n) times and is likely to TLE for large n. Consider restructuring to compute all root scores in a single rerooting pass instead.

Suggested implementation:

        # Rerooting DP: compute all root scores in O(n)
        # 1) First DFS: compute subtree scores when rooted at an arbitrary node (e.g. 0)
        subtree = [0] * n

        def dfs_down(node: int, parent: int) -> int:
            best = values[node]
            for child in graph[node]:
                if child != parent:
                    child_score = dfs_down(child, node)
                    if child_score > 0:
                        best += child_score
            subtree[node] = best
            return best

        dfs_down(0, -1)

        # 2) Second DFS: reroot, propagating contributions from the parent side
        res = [0] * n

        def dfs_reroot(node: int, parent: int, parent_contrib: int) -> None:
            # Score when rooted at `node` = its subtree plus positive contribution from parent side
            res[node] = subtree[node] + max(0, parent_contrib)

            # Collect children (excluding parent) with their positive contributions
            children = []
            for child in graph[node]:
                if child == parent:
                    continue
                children.append((child, max(0, subtree[child])))

            m = len(children)
            prefix = [0] * (m + 1)
            suffix = [0] * (m + 1)

            for i in range(m):
                prefix[i + 1] = prefix[i] + children[i][1]
                suffix[m - 1 - i] = suffix[m - i] + children[m - 1 - i][1]

            for i, (child, child_contrib) in enumerate(children):
                # Contribution to pass to this child from "everything except this child"
                without_child = values[node] + prefix[i] + suffix[i + 1]
                if parent_contrib > 0:
                    without_child += parent_contrib
                dfs_reroot(child, node, without_child)

        dfs_reroot(0, -1, 0)

        return res

This implementation assumes:

  1. The node values are stored in an iterable named values indexed from 0 to n-1.
  2. graph is an adjacency list for a tree with n nodes and is already built earlier in the function.

If your current dfs had a different initialization for best (e.g. starting from 0 instead of values[node] or incorporating other state), you should mirror that initialization in dfs_down to keep the semantics identical. Also remove or inline the original dfs if it is no longer used.

Comment on lines +6 to +15
prefix = [0] * (n + 1)
for i in range(n):
prefix[i + 1] = prefix[i] + damage[i]

# For each starting position i, calculate score
res = 0
for i in range(n):
current_hp = hp
score = 0
for j in range(i, n):
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suggestion (performance): The current O(n²) nested loops and unused prefix sum may be inefficient compared to prefix-based or two-pointer approaches.

The computed prefix array is unused; current_hp is still updated via a full inner loop (current_hp -= damage[j]). For large inputs this O(n²) pattern may be too slow. Consider using the prefix sums directly (e.g., prefix[j + 1] - prefix[i]) to enable a more efficient approach such as binary searching the maximal j per i, or otherwise reducing the complexity.

Suggested implementation:

from bisect import bisect_left


class Solution:
    def totalScore(self, hp: int, damage: List[int], requirement: List[int]) -> int:
        n = len(damage)

        # Prefix sums for damage
        prefix = [0] * (n + 1)
        for i in range(n):
            prefix[i + 1] = prefix[i] + damage[i]

        # Count valid (i, j) pairs using prefix sums and binary search.
        # Condition for starting at i and ending at j:
        #   hp - (prefix[j + 1] - prefix[i]) >= requirement[j]
        #   => prefix[i] >= requirement[j] - hp + prefix[j + 1]
        res = 0
        for j in range(n):
            threshold = requirement[j] - hp + prefix[j + 1]
            # Find the first i in [0, j] such that prefix[i] >= threshold
            idx = bisect_left(prefix, threshold, 0, j + 1)
            if idx <= j:
                res += (j - idx + 1)

        return res
  1. Ensure there is not already a conflicting from bisect import bisect_left import at the top of the file. If imports are grouped elsewhere, you may instead want to add from bisect import bisect_left alongside the existing imports rather than directly before class Solution.
  2. This approach assumes that damage elements are non-negative so that prefix is non-decreasing (a typical assumption in HP/damage problems). If negative values are allowed, this monotonicity-based bisect_left logic must be revisited.

@romankurnovskii romankurnovskii merged commit 62e101b into main Dec 8, 2025
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@romankurnovskii romankurnovskii deleted the problems-2390-2542-3753-3759-3760-3761-3762-3765-3766-3767-3768-3769-3770-3771-3772 branch December 8, 2025 08:46
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Actionable comments posted: 9

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)
solutions/3762/01.py (1)

1-14: Add missing List import from typing

Line 2 uses List[int] in the type hints, but there is no import statement visible in the provided code. Using List[int] without importing List from typing will raise NameError: name 'List' is not defined at runtime on Python versions before 3.9.

Add the import:

+from typing import List
+
 class Solution:
     def minOperations(self, nums: List[int], k: int) -> int:

Alternatively, use the built-in generic syntax on Python 3.9+: list[int] instead of List[int], or add from __future__ import annotations at the top for forward compatibility.

🧹 Nitpick comments (1)
solutions/3767/01.py (1)

1-23: Consider early break in the greedy loop for efficiency

The greedy algorithm is correct: sorting deltas in descending order and applying the largest switches maximizes points. However, since deltas is sorted descending, once a non-positive delta is encountered, further iterations cannot improve total. You can optionally break early to skip unnecessary work:

         for i in range(n - k):
+            if deltas[i] <= 0:
+                break
             total += deltas[i]
             res = max(res, total)

This optimization saves iterations when many negative or zero deltas exist, though it doesn't affect correctness.

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📒 Files selected for processing (23)
  • data/leetcode-problems.json (1 hunks)
  • explanations/2390/en.md (1 hunks)
  • explanations/2542/en.md (1 hunks)
  • explanations/3762/en.md (1 hunks)
  • explanations/3765/en.md (1 hunks)
  • explanations/3766/en.md (1 hunks)
  • explanations/3767/en.md (1 hunks)
  • explanations/3768/en.md (1 hunks)
  • explanations/3769/en.md (1 hunks)
  • explanations/3770/en.md (1 hunks)
  • explanations/3771/en.md (1 hunks)
  • explanations/3772/en.md (1 hunks)
  • solutions/2390/01.py (1 hunks)
  • solutions/2542/01.py (1 hunks)
  • solutions/3762/01.py (1 hunks)
  • solutions/3765/01.py (1 hunks)
  • solutions/3766/01.py (1 hunks)
  • solutions/3767/01.py (1 hunks)
  • solutions/3768/01.py (1 hunks)
  • solutions/3769/01.py (1 hunks)
  • solutions/3770/01.py (1 hunks)
  • solutions/3771/01.py (1 hunks)
  • solutions/3772/01.py (1 hunks)
🧰 Additional context used
🧬 Code graph analysis (1)
solutions/3767/01.py (1)
solutions/2542/01.py (1)
  • Solution (1-27)
🪛 GitHub Actions: PR JSON Validation
data/leetcode-problems.json

[error] 1-1: JSON file is not normalized. Run './scripts/normalize_json.py data/leetcode-problems.json' and commit the changes.


[warning] 26416-26416: No newline at end of file detected in data/leetcode-problems.json.

🪛 LanguageTool
explanations/3770/en.md

[duplication] ~9-~9: Possible typo: you repeated a word.
Context: ...<= 5 * 10^5` - Time Complexity: O(n log log n) for sieve + O(p²) for consecutive su...

(ENGLISH_WORD_REPEAT_RULE)


[duplication] ~20-~20: Possible typo: you repeated a word.
Context: ... Eratosthenes to mark all primes in O(n log log n), then compute consecutive sums - **E...

(ENGLISH_WORD_REPEAT_RULE)

explanations/3771/en.md

[style] ~11-~11: As an alternative to the over-used intensifier ‘very’, consider replacing this phrase.
Context: ...efix sums - Edge Case: If damage is very large, HP may become negative quickly **1.2 ...

(EN_WEAK_ADJECTIVE)

🪛 markdownlint-cli2 (0.18.1)
explanations/3766/en.md

42-42: Table column count
Expected: 5; Actual: 7; Too many cells, extra data will be missing

(MD056, table-column-count)


43-43: Table column count
Expected: 5; Actual: 7; Too many cells, extra data will be missing

(MD056, table-column-count)


44-44: Table column count
Expected: 5; Actual: 7; Too many cells, extra data will be missing

(MD056, table-column-count)

🪛 Ruff (0.14.7)
solutions/3768/01.py

2-2: Undefined name List

(F821)

solutions/3767/01.py

2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)

solutions/3766/01.py

2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)

solutions/3772/01.py

2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)

solutions/2542/01.py

2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)


4-4: zip() without an explicit strict= parameter

Add explicit value for parameter strict=

(B905)

solutions/3771/01.py

2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)

solutions/3769/01.py

2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)

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  • GitHub Check: Sourcery review
🔇 Additional comments (9)
solutions/3765/01.py (1)

1-30: Complete-prime implementation is correct and efficient

The is_prime helper and the prefix/suffix loops correctly enforce that every prefix and suffix of num is prime, with reasonable √n primality checks and early returns. No issues spotted.

explanations/3769/en.md (1)

1-50: Binary-reflection explanation matches the implemented strategy

The write-up clearly defines binary reflection, states the correct O(n log n) complexity, and explains sorting by (reflection, original) with a concrete trace table that matches solutions/3769/01.py. Looks consistent and ready to ship.

solutions/3770/01.py (1)

1-27: Consecutive-prime-sum sieve solution looks correct

The sieve construction, extraction of all primes ≤ n, and the double loop over start/end with current_sum > n early breaks correctly enumerate all consecutive-prime sums and track the largest one that is still prime and ≤ n. No correctness or maintainability issues detected.

solutions/3769/01.py (1)

1-11: Add List import for type hints; reflection-based sorting logic is correct

The sortByReflection implementation correctly computes binary reflections via bin(n)[2:], reversal, and int(..., 2), then sorts by (binary_reflection(x), x) to handle tie-breaking. However, the code uses List[int] without an import statement visible in lines 1-11. Depending on Python version and whether from __future__ import annotations is present elsewhere in the file, this may cause a NameError. Add the typing import:

+from typing import List
+
 class Solution:
     def sortByReflection(self, nums: List[int]) -> List[int]:
solutions/2390/01.py (1)

1-16: Stack-based implementation is correct and efficient

The logic cleanly matches the problem specification (push non-*, pop on *) with O(n) time and O(n) space and a clear res result variable. No issues from a correctness or style standpoint.

explanations/2390/en.md (1)

1-59: Explanation aligns well with the implemented solution

Problem restatement, complexity, stack strategy, and the step-by-step trace are all consistent with the Python implementation and standard solutions for 2390.

explanations/3768/en.md (1)

1-52: Clear and accurate description of the Fenwick + sliding-window approach

The explanation’s constraints, complexity, decomposition, and example all align with the implemented algorithm in solutions/3768/01.py, and it’s technically sound.

data/leetcode-problems.json (2)

26360-26414: Data entries are well-structured and consistent.

The 8 new problem entries (3765–3772) follow the established schema with all required fields (id, category, title, difficulty, link) properly populated. Categories align with problem domains, difficulty levels are appropriate, and LeetCode URLs follow the expected pattern. Content looks good once the JSON normalization and EOF newline issues are resolved.


26360-26414: The file is already properly formatted and does not require the suggested actions.

The JSON file already has:

  • Keys in numeric order
  • Proper 2-space indentation
  • A newline at EOF

Running the normalization script is unnecessary; the file meets all formatting requirements as-is. The problem entries (3765-3772) are correctly structured and positioned.

Likely an incorrect or invalid review comment.

Comment on lines +40 to +45
| Number | Binary | Closest Palindrome | Operations | Result |
|--------|--------|-------------------|------------|--------|
| 1 | 1 | 1 | |0| = 0 | 0 |
| 2 | 10 | 3 (11) | |2-3| = 1 | 1 |
| 4 | 100 | 3 (11) | |4-3| = 1 | 1 |

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⚠️ Potential issue | 🟡 Minor

Fix table formatting and clarify operations expressions

The absolute-value notation in the Operations column introduces extra | characters, breaking the table (and triggering MD056), and the first row’s formula is a bit unclear.

You can avoid both issues by rewriting the Operations cells without | characters:

-| 1 | 1 | 1 | |0| = 0 | 0 |
-| 2 | 10 | 3 (11) | |2-3| = 1 | 1 |
-| 4 | 100 | 3 (11) | |4-3| = 1 | 1 |
+| 1 | 1 | 1 | abs(1-1) = 0 | 0 |
+| 2 | 10 | 3 (11) | abs(2-3) = 1 | 1 |
+| 4 | 100 | 3 (11) | abs(4-3) = 1 | 1 |

This keeps the table well-formed and makes the math explicit.

🧰 Tools
🪛 markdownlint-cli2 (0.18.1)

42-42: Table column count
Expected: 5; Actual: 7; Too many cells, extra data will be missing

(MD056, table-column-count)


43-43: Table column count
Expected: 5; Actual: 7; Too many cells, extra data will be missing

(MD056, table-column-count)


44-44: Table column count
Expected: 5; Actual: 7; Too many cells, extra data will be missing

(MD056, table-column-count)

🤖 Prompt for AI Agents
In explanations/3766/en.md around lines 40–45, the Operations column uses
literal '|' characters for absolute-value notation which breaks the Markdown
table; replace those with a plain, pipe-free expression (e.g., use abs(1-1) = 0,
abs(2-3) = 1, abs(4-3) = 1) and update the first row to explicitly show abs(1-1)
= 0 so the table cells contain no '|' characters and render correctly.

Comment on lines +32 to +54
**2.1 Initialization & Example Setup:**
Let's use the example: `technique1 = [5,2,10]`, `technique2 = [10,3,8]`, `k = 2`
- Initial total: 5 + 2 + 10 = 17
- Deltas: [10-5, 3-2, 8-10] = [5, 1, -2]

**2.2 Start Processing:**
We sort deltas and apply the best switches.

**2.3 Trace Walkthrough:**

| Step | Total | Delta Applied | New Total | Max |
|------|-------|---------------|-----------|-----|
| Initial | 17 | - | - | 17 |
| Apply delta 5 | 17 | +5 | 22 | 22 |
| Apply delta 1 | 22 | +1 | 23 | 23 |

Since k=2, we can switch at most 1 task (n-k=1). We apply the largest delta (5).

**2.4 Increment and Loop:**
After applying the best (n-k) deltas, we have the maximum.

**2.5 Return Result:**
The maximum total is 22 (switching task 0 from technique1 to technique2: 2 + 10 + 10 = 22).
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⚠️ Potential issue | 🟡 Minor

Fix example walkthrough to respect the k-constraint.

For the example technique1 = [5,2,10], technique2 = [10,3,8], k = 2 (so n-k = 1), the table currently applies both deltas 5 and 1 (Lines 45–46), even though we’re allowed to switch at most one task away from technique1. Later you correctly state that we can switch at most one task.

To avoid confusion, adjust the trace so that only the best single delta (5) is applied, or explicitly mark the second row as an invalid step. Right now, the table and the textual explanation conflict.

🤖 Prompt for AI Agents
In explanations/3767/en.md around lines 32 to 54, the example walkthrough
violates the k-constraint by applying two deltas while k=2 (n-k=1): update the
trace so only the single largest delta (+5) is applied (show Initial -> Apply
delta 5 -> New Total 22 -> Max 22) and remove or mark the second delta
application row as invalid, and adjust the surrounding text to state explicitly
that only one task can be switched.

Comment on lines +7 to +21
**1.1 Constraints & Complexity:**
- Input size: `1 <= n <= 10^5`, `1 <= hp <= 10^9`
- **Time Complexity:** O(n²) for the straightforward approach, can be optimized with prefix sums
- **Space Complexity:** O(n) for prefix sums
- **Edge Case:** If damage is very large, HP may become negative quickly

**1.2 High-level approach:**
For each starting position, simulate the journey through remaining rooms, tracking HP and counting points when HP >= requirement after taking damage.

![Dungeon simulation visualization](https://assets.leetcode.com/static_assets/others/dungeon-simulation.png)

**1.3 Brute force vs. optimized strategy:**
- **Brute Force:** For each starting position, simulate the entire journey, which is O(n²)
- **Optimized Strategy:** Use prefix sums to quickly calculate cumulative damage, but still need to check each room, achieving O(n²) in worst case
- **Emphasize the optimization:** Prefix sums help but we still need to check each room's requirement
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⚠️ Potential issue | 🟠 Major

Clarify O(n²) complexity against the stated n ≤ 10^5 constraint

With n up to 10^5 (Line 8), the described per-start simulation in O(n²) would do on the order of 10^10 iterations in the worst case, which is unlikely to be acceptable in Python. It would be good to clarify whether this is only a conceptual/brute-force description (and a faster solution is intended in code), or to outline a genuinely sub‑quadratic approach that matches these constraints.

🧰 Tools
🪛 LanguageTool

[style] ~11-~11: As an alternative to the over-used intensifier ‘very’, consider replacing this phrase.
Context: ...efix sums - Edge Case: If damage is very large, HP may become negative quickly **1.2 ...

(EN_WEAK_ADJECTIVE)

Comment on lines +7 to +21
**1.1 Constraints & Complexity:**
- Input size: `2 <= n <= 10^5`
- **Time Complexity:** O(n²) for naive approach, can be optimized with tree DP
- **Space Complexity:** O(n) for the tree and DP arrays
- **Edge Case:** If all nodes are bad, the best score for each node might be -1

**1.2 High-level approach:**
We use tree dynamic programming with rerooting. For each node as root, we perform DFS to find the maximum score of connected subgraphs containing that root.

![Tree DP visualization](https://assets.leetcode.com/static_assets/others/tree-dp-rerooting.png)

**1.3 Brute force vs. optimized strategy:**
- **Brute Force:** For each node, try all possible connected subgraphs, which is exponential
- **Optimized Strategy:** Use tree DP where for each root, we calculate the best subtree score, achieving O(n²) time
- **Emphasize the optimization:** Tree structure allows efficient calculation of subtree scores
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⚠️ Potential issue | 🟠 Major

Resolve confusion around ‘naive’ vs ‘optimized’ complexity and scalability

Lines 8–10 say the naive time complexity is O(n²) and that it “can be optimized with tree DP,” but Section 1.3 still presents the tree-DP strategy as O(n²). This is confusing, and with n ≤ 10^5 a quadratic algorithm is borderline at best. Please clarify which approach is actually considered brute force (likely exponential over subgraphs) and what complexity your tree-DP solution targets (ideally O(n) with standard rerooting), or explicitly state if you’re intentionally presenting an O(n²) solution despite these constraints.

🤖 Prompt for AI Agents
In explanations/3772/en.md around lines 7–21, the complexity descriptions are
inconsistent: replace the claim that the “naive” approach is O(n²) with that
brute-force over all connected subgraphs is exponential, and update Section 1.3
to state the tree DP with standard rerooting runs in O(n) overall (or explicitly
state the achieved time complexity if your implementation differs), keeping
space O(n); make the wording consistent across Sections 1.1 and 1.3 and add a
short note if you intentionally present an O(n²) variant explaining why.

Comment on lines +1 to +7
class Solution:
def maxScore(self, nums1: List[int], nums2: List[int], k: int) -> int:
# Sort pairs by nums2 in descending order
pairs = sorted(zip(nums1, nums2), key=lambda x: x[1], reverse=True)

import heapq
# Use min heap to maintain k largest nums1 values
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⚠️ Potential issue | 🔴 Critical

Import List and consider explicit strict on zip.

  • List in the signature (Line 2) is undefined; this will raise at import time in this repo. Add a typing import, e.g.:
+from typing import List
+
 class Solution:
     def maxScore(self, nums1: List[int], nums2: List[int], k: int) -> int:
-        # Sort pairs by nums2 in descending order
-        pairs = sorted(zip(nums1, nums2), key=lambda x: x[1], reverse=True)
+        # Sort pairs by nums2 in descending order
+        pairs = sorted(
+            zip(nums1, nums2, strict=False),
+            key=lambda x: x[1],
+            reverse=True,
+        )

(Keeping strict=False preserves current behavior while satisfying B905; if you want a hard check that the arrays have equal length, use strict=True instead.)

🧰 Tools
🪛 Ruff (0.14.7)

2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)


4-4: zip() without an explicit strict= parameter

Add explicit value for parameter strict=

(B905)

🤖 Prompt for AI Agents
In solutions/2542/01.py around lines 1 to 7, the type name List used in the
function signature is not imported and zip should be explicit about length
behavior; add "from typing import List" at the top of the file and change the
zip call to include strict=False (or strict=True if you want to enforce equal
lengths) so the sorted(zip(...), key=..., reverse=True) becomes
sorted(zip(nums1, nums2, strict=False), key=..., reverse=True).

Comment on lines +1 to +23
class Solution:
def minOperations(self, nums: List[int]) -> List[int]:
# Precompute binary palindromes up to 5000
def is_binary_palindrome(n):
binary = bin(n)[2:]
return binary == binary[::-1]

# Generate all binary palindromes
palindromes = []
for i in range(1, 5001):
if is_binary_palindrome(i):
palindromes.append(i)

res = []
for num in nums:
# Find closest palindrome
min_ops = float('inf')
for pal in palindromes:
ops = abs(num - pal)
min_ops = min(min_ops, ops)
res.append(min_ops)

return res
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⚠️ Potential issue | 🟡 Minor

🧩 Analysis chain

🏁 Script executed:

cd solutions/3766 && cat -n 01.py

Repository: romankurnovskii/leetcode-apps

Length of output: 958


🏁 Script executed:

# Check other solution files to see if List is imported or used without import
find solutions -name "*.py" -type f | head -20 | xargs -I {} sh -c 'echo "=== {} ===" && head -5 "{}"'

Repository: romankurnovskii/leetcode-apps

Length of output: 3838


🏁 Script executed:

cat -n solutions/1029/01.py && echo "---" && cat -n solutions/1046/01.py

Repository: romankurnovskii/leetcode-apps

Length of output: 1481


Add missing List import from typing

The type annotation on line 2 uses List[int] without importing it from the typing module. While this works in LeetCode's execution environment (which auto-provides typing imports), it violates Python's import conventions and would cause a NameError if run locally.

Add the import at the top of the file:

+from typing import List
+
 class Solution:
     def minOperations(self, nums: List[int]) -> List[int]:

This same pattern appears in other files across the repository (e.g., solutions/1029/01.py, solutions/1046/01.py), so consider standardizing imports across all solution files.

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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
class Solution:
def minOperations(self, nums: List[int]) -> List[int]:
# Precompute binary palindromes up to 5000
def is_binary_palindrome(n):
binary = bin(n)[2:]
return binary == binary[::-1]
# Generate all binary palindromes
palindromes = []
for i in range(1, 5001):
if is_binary_palindrome(i):
palindromes.append(i)
res = []
for num in nums:
# Find closest palindrome
min_ops = float('inf')
for pal in palindromes:
ops = abs(num - pal)
min_ops = min(min_ops, ops)
res.append(min_ops)
return res
from typing import List
class Solution:
def minOperations(self, nums: List[int]) -> List[int]:
# Precompute binary palindromes up to 5000
def is_binary_palindrome(n):
binary = bin(n)[2:]
return binary == binary[::-1]
# Generate all binary palindromes
palindromes = []
for i in range(1, 5001):
if is_binary_palindrome(i):
palindromes.append(i)
res = []
for num in nums:
# Find closest palindrome
min_ops = float('inf')
for pal in palindromes:
ops = abs(num - pal)
min_ops = min(min_ops, ops)
res.append(min_ops)
return res
🧰 Tools
🪛 Ruff (0.14.7)

2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)

🤖 Prompt for AI Agents
In solutions/3766/01.py around lines 1 to 23, the type annotation List[int] is
used but List is not imported; add the missing import "from typing import List"
at the top of the file so the annotation resolves, and apply the same import to
other solution files that use List (e.g., solutions/1029/01.py,
solutions/1046/01.py) to standardize imports across the repo.

Comment on lines +1 to +57
class Solution:
def minInversionCount(self, nums: List[int], k: int) -> int:
# Compress numbers to range [1, n]
sorted_nums = sorted(set(nums))
comp_map = {val: idx + 1 for idx, val in enumerate(sorted_nums)}
compressed = [comp_map[num] for num in nums]
n = len(compressed)

# Fenwick Tree (Binary Indexed Tree) for counting
class FenwickTree:
def __init__(self, size):
self.n = size
self.tree = [0] * (size + 1)

def update(self, idx, delta):
while idx <= self.n:
self.tree[idx] += delta
idx += idx & -idx

def query(self, idx):
res = 0
while idx > 0:
res += self.tree[idx]
idx -= idx & -idx
return res

# Initialize Fenwick Tree
ft = FenwickTree(n)

# Calculate inversion count for first window
inv_count = 0
for i in range(k):
# Count numbers greater than compressed[i] in current window
inv_count += i - ft.query(compressed[i])
ft.update(compressed[i], 1)

res = inv_count

# Slide window
for i in range(k, n):
# Remove leftmost element
ft.update(compressed[i - k], -1)
# Count numbers smaller than removed element
removed = compressed[i - k]
smaller = ft.query(removed - 1)
inv_count -= smaller

# Add new element
new_val = compressed[i]
# Count numbers greater than new element in current window
greater = (k - 1) - ft.query(new_val)
inv_count += greater
ft.update(new_val, 1)

res = min(res, inv_count)

return res
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⚠️ Potential issue | 🔴 Critical

🧩 Analysis chain

🏁 Script executed:

cat -n solutions/3768/01.py

Repository: romankurnovskii/leetcode-apps

Length of output: 2425


🏁 Script executed:

head -20 solutions/3768/01.py

Repository: romankurnovskii/leetcode-apps

Length of output: 818


🏁 Script executed:

git ls-files solutions/3768/ | head -20

Repository: romankurnovskii/leetcode-apps

Length of output: 93


🏁 Script executed:

find solutions/3768 -type f -name "*.py" | head -10

Repository: romankurnovskii/leetcode-apps

Length of output: 93


🏁 Script executed:

head -5 solutions/3768/*.py 2>/dev/null | head -30

Repository: romankurnovskii/leetcode-apps

Length of output: 309


🏁 Script executed:

# Check if there are README or template files that might clarify the structure
ls -la solutions/3768/

Repository: romankurnovskii/leetcode-apps

Length of output: 244


🏁 Script executed:

# Check a few other solution directories to see the import pattern
find solutions -maxdepth 2 -name "01.py" -type f | head -5 | xargs head -3

Repository: romankurnovskii/leetcode-apps

Length of output: 730


🏁 Script executed:

# Check if there's a project-wide configuration or README
find . -maxdepth 2 -name "README*" -o -name "setup.py" -o -name "pyproject.toml" | head -5

Repository: romankurnovskii/leetcode-apps

Length of output: 84


🏁 Script executed:

# Check the README to understand the project structure
head -30 README.md

Repository: romankurnovskii/leetcode-apps

Length of output: 1447


Add missing List import from typing

List is used in the type annotation on line 2 but is never imported. This will raise a NameError at runtime. Add the import at the top of the file:

+from typing import List
+
 class Solution:
     def minInversionCount(self, nums: List[int], k: int) -> int:

The algorithm itself—coordinate compression, Fenwick Tree implementation, first-window inversion count initialization, and sliding-window updates—is correct and efficiently computes the minimum inversion count across all subarrays of size k.

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
class Solution:
def minInversionCount(self, nums: List[int], k: int) -> int:
# Compress numbers to range [1, n]
sorted_nums = sorted(set(nums))
comp_map = {val: idx + 1 for idx, val in enumerate(sorted_nums)}
compressed = [comp_map[num] for num in nums]
n = len(compressed)
# Fenwick Tree (Binary Indexed Tree) for counting
class FenwickTree:
def __init__(self, size):
self.n = size
self.tree = [0] * (size + 1)
def update(self, idx, delta):
while idx <= self.n:
self.tree[idx] += delta
idx += idx & -idx
def query(self, idx):
res = 0
while idx > 0:
res += self.tree[idx]
idx -= idx & -idx
return res
# Initialize Fenwick Tree
ft = FenwickTree(n)
# Calculate inversion count for first window
inv_count = 0
for i in range(k):
# Count numbers greater than compressed[i] in current window
inv_count += i - ft.query(compressed[i])
ft.update(compressed[i], 1)
res = inv_count
# Slide window
for i in range(k, n):
# Remove leftmost element
ft.update(compressed[i - k], -1)
# Count numbers smaller than removed element
removed = compressed[i - k]
smaller = ft.query(removed - 1)
inv_count -= smaller
# Add new element
new_val = compressed[i]
# Count numbers greater than new element in current window
greater = (k - 1) - ft.query(new_val)
inv_count += greater
ft.update(new_val, 1)
res = min(res, inv_count)
return res
from typing import List
class Solution:
def minInversionCount(self, nums: List[int], k: int) -> int:
# Compress numbers to range [1, n]
sorted_nums = sorted(set(nums))
comp_map = {val: idx + 1 for idx, val in enumerate(sorted_nums)}
compressed = [comp_map[num] for num in nums]
n = len(compressed)
# Fenwick Tree (Binary Indexed Tree) for counting
class FenwickTree:
def __init__(self, size):
self.n = size
self.tree = [0] * (size + 1)
def update(self, idx, delta):
while idx <= self.n:
self.tree[idx] += delta
idx += idx & -idx
def query(self, idx):
res = 0
while idx > 0:
res += self.tree[idx]
idx -= idx & -idx
return res
# Initialize Fenwick Tree
ft = FenwickTree(n)
# Calculate inversion count for first window
inv_count = 0
for i in range(k):
# Count numbers greater than compressed[i] in current window
inv_count += i - ft.query(compressed[i])
ft.update(compressed[i], 1)
res = inv_count
# Slide window
for i in range(k, n):
# Remove leftmost element
ft.update(compressed[i - k], -1)
# Count numbers smaller than removed element
removed = compressed[i - k]
smaller = ft.query(removed - 1)
inv_count -= smaller
# Add new element
new_val = compressed[i]
# Count numbers greater than new element in current window
greater = (k - 1) - ft.query(new_val)
inv_count += greater
ft.update(new_val, 1)
res = min(res, inv_count)
return res
🧰 Tools
🪛 Ruff (0.14.7)

2-2: Undefined name List

(F821)

🤖 Prompt for AI Agents
In solutions/3768/01.py around lines 1 to 57, the type annotation uses List but
the symbol is not imported; add "from typing import List" at the top of the file
(as the first import) so the type annotation resolves, then run a quick
lint/type check to confirm no other missing imports.

Comment on lines +1 to +21
class Solution:
def totalScore(self, hp: int, damage: List[int], requirement: List[int]) -> int:
n = len(damage)

# Prefix sums for damage
prefix = [0] * (n + 1)
for i in range(n):
prefix[i + 1] = prefix[i] + damage[i]

# For each starting position i, calculate score
res = 0
for i in range(n):
current_hp = hp
score = 0
for j in range(i, n):
current_hp -= damage[j]
if current_hp >= requirement[j]:
score += 1
res += score

return res
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⚠️ Potential issue | 🟠 Major

🧩 Analysis chain

🏁 Script executed:

# First, explore the directory structure
cd solutions/3771 && find . -type f -name "*.py" -o -name "*.md" -o -name "*.txt" | head -20

Repository: romankurnovskii/leetcode-apps

Length of output: 80


🏁 Script executed:

# Check what files exist in the directory
ls -la solutions/3771/

Repository: romankurnovskii/leetcode-apps

Length of output: 244


🏁 Script executed:

# Read the solution file to see full context
cat -n solutions/3771/01.py

Repository: romankurnovskii/leetcode-apps

Length of output: 859


🏁 Script executed:

# Search for any problem description or explanation
rg -i "explanation|problem|constraint|example" solutions/3771/ -A 3 -B 1

Repository: romankurnovskii/leetcode-apps

Length of output: 55


🏁 Script executed:

# Check if there's a README or problem description at the root or in solutions/ directory
find solutions -name "README*" -o -name "*.md" | head -20

Repository: romankurnovskii/leetcode-apps

Length of output: 55


🏁 Script executed:

# Check the root directory for any documentation
ls -la | head -20

Repository: romankurnovskii/leetcode-apps

Length of output: 1269


🏁 Script executed:

# Search for any reference to problem 3771 or constraints
rg "3771|totalScore" . --max-count=10

Repository: romankurnovskii/leetcode-apps

Length of output: 440


🏁 Script executed:

# Check the explanations directory for problem 3771
ls -la explanations/3771/

Repository: romankurnovskii/leetcode-apps

Length of output: 244


🏁 Script executed:

# Read the problem description from the data file
jq '.["3771"]' data/leetcode-problems.json

Repository: romankurnovskii/leetcode-apps

Length of output: 266


🏁 Script executed:

# Search for any explanation files related to 3771
find explanations/3771 -type f

Repository: romankurnovskii/leetcode-apps

Length of output: 96


🏁 Script executed:

# Read the explanation file
cat -n explanations/3771/en.md

Repository: romankurnovskii/leetcode-apps

Length of output: 2897


Add missing List import and remove unused prefix sums code.

  • List in the signature (line 2) is undefined; add the required import:

    +from typing import List
    +
     class Solution:
  • The prefix array (lines 6–8) is unused dead code that should be removed.

The O(n²) complexity is unavoidable for this problem given the constraints (n ≤ 10⁵): you must check each (i, j) pair where i is the starting room and j ranges from i to n−1. Prefix sums do not improve the worst-case complexity.

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
class Solution:
def totalScore(self, hp: int, damage: List[int], requirement: List[int]) -> int:
n = len(damage)
# Prefix sums for damage
prefix = [0] * (n + 1)
for i in range(n):
prefix[i + 1] = prefix[i] + damage[i]
# For each starting position i, calculate score
res = 0
for i in range(n):
current_hp = hp
score = 0
for j in range(i, n):
current_hp -= damage[j]
if current_hp >= requirement[j]:
score += 1
res += score
return res
from typing import List
class Solution:
def totalScore(self, hp: int, damage: List[int], requirement: List[int]) -> int:
n = len(damage)
# For each starting position i, calculate score
res = 0
for i in range(n):
current_hp = hp
score = 0
for j in range(i, n):
current_hp -= damage[j]
if current_hp >= requirement[j]:
score += 1
res += score
return res
🧰 Tools
🪛 Ruff (0.14.7)

2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)

🤖 Prompt for AI Agents
In solutions/3771/01.py around lines 1 to 21, the function signature uses List
but the typing.List import is missing and the prefix sums array is unused dead
code; fix by adding "from typing import List" at the top of the file (or include
List in existing typing imports) and remove the prefix array creation and its
population (lines that create and fill prefix) so only the necessary O(n²) loops
remain.

Comment on lines +1 to +35
class Solution:
def maxSubgraphScore(self, n: int, edges: List[List[int]], good: List[int]) -> List[int]:
# Build tree
from collections import defaultdict
graph = defaultdict(list)
for u, v in edges:
graph[u].append(v)
graph[v].append(u)

# Rerooting DP
# dp[node] = max score of connected subgraph containing node
# We use tree DP with rerooting

# First, calculate for each node the best subtree score
def dfs(node, parent):
# Score contribution of this node
node_score = 1 if good[node] else -1

# Best score including this node and its children
best = node_score
for child in graph[node]:
if child != parent:
child_score = dfs(child, node)
# Include child if it improves the score
if child_score > 0:
best += child_score
return best

# For each node as root, calculate max score
res = []
for root in range(n):
score = dfs(root, -1)
res.append(score)

return res
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⚠️ Potential issue | 🟠 Major

🧩 Analysis chain

🏁 Script executed:

cat -n solutions/3772/01.py

Repository: romankurnovskii/leetcode-apps

Length of output: 1555


🏁 Script executed:

# Look for explanation or constraints
find solutions/3772 -type f | head -20

Repository: romankurnovskii/leetcode-apps

Length of output: 93


🌐 Web query:

LeetCode 3772 maxSubgraphScore constraints

💡 Result:

I couldn't find a LeetCode problem titled "maxSubgraphScore" or number 3772 with that name. Do you mean a different problem title or number (e.g., "maximum subgraph score", a contest problem, or a problem ID)? If you want, I can search LeetCode and other sources again — tell me the exact problem link, title, or paste the statement.


Add missing typing import and address O(n²) complexity despite "rerooting DP" claim.

  • List in the signature (line 2) is undefined; add the import:
+from typing import List
+
 class Solution:
     def maxSubgraphScore(self, n: int, edges: List[List[int]], good: List[int]) -> List[int]:
  • Despite the "Rerooting DP" comment (lines 10–12), the code runs a full dfs for every root (lines 31–33), yielding O(n²) time complexity. True rerooting DP computes answers in O(n) or O(n log n) via two passes: one post-order DFS to compute subtree scores, then one pre-order DFS to propagate changes across roots. This implementation does not match that pattern.

  • The recursive dfs can exceed Python's recursion limit (~1000) on deep trees if n is large.

Consider either implementing true rerooting DP to match the explanation and achieve O(n) complexity, or explicitly document that this is a brute-force O(n²) solution.

🧰 Tools
🪛 Ruff (0.14.7)

2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)


2-2: Undefined name List

(F821)

🤖 Prompt for AI Agents
In solutions/3772/01.py around lines 1–35, fix three issues: add the missing
typing import (e.g., "from typing import List") at the top; replace the current
O(n²) approach (calling dfs for every root) with a true rerooting DP: perform
one post-order DFS to compute dp_down[node] = max score of connected subgraph
inside node's subtree including node, then a pre-order DFS to propagate
contributions and compute final_answer[node] by re-rooting using parent-to-child
transfers (avoid re-running full DFS per root); and handle deep recursion by
either setting sys.setrecursionlimit to a safe value or converting the DFSs to
iterative stacks. Ensure the final result uses the two-pass rerooting values and
remove the per-root dfs loop.

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