Leetcode

Collection of LeetCode questions to ace the coding interview!

LeetCode Topics

Array

0015-3sum
0031-next-permutation
0046-permutations
0048-rotate-image
0051-n-queens
0053-maximum-subarray
0056-merge-intervals
0064-minimum-path-sum
0074-search-a-2d-matrix
0075-sort-colors
0078-subsets
0088-merge-sorted-array
0090-subsets-ii
0118-pascals-triangle
0121-best-time-to-buy-and-sell-stock
0169-majority-element
0215-kth-largest-element-in-an-array
0229-majority-element-ii
0287-find-the-duplicate-number
0300-longest-increasing-subsequence
0368-largest-divisible-subset
0416-partition-equal-subset-sum
0496-next-greater-element-i
0503-next-greater-element-ii
0624-maximum-distance-in-arrays
0632-smallest-range-covering-elements-from-k-lists
0719-find-k-th-smallest-pair-distance
0859-design-circular-deque
0870-magic-squares-in-grid
0890-lemonade-change
0921-spiral-matrix-iii
0952-word-subsets
0999-regions-cut-by-slashes
1002-maximum-width-ramp
1240-stone-game-ii
1256-rank-transform-of-an-array
1350-remove-sub-folders-from-the-filesystem
1396-count-servers-that-communicate
1402-count-square-submatrices-with-all-ones
1497-design-a-stack-with-increment-operation
1524-string-matching-in-an-array
1656-count-good-triplets
1691-minimum-number-of-days-to-disconnect-island
1694-make-sum-divisible-by-p
1786-count-the-number-of-consistent-strings
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
1923-sentence-similarity-iii
1993-sum-of-all-subset-xor-totals
2006-find-the-student-that-will-replace-the-chalk
2054-the-number-of-the-smallest-unoccupied-chair
2155-find-missing-observations
2163-kth-distinct-string-in-an-array
2170-count-number-of-maximum-bitwise-or-subsets
2262-solving-questions-with-brainpower
2265-partition-array-according-to-given-pivot
2277-count-equal-and-divisible-pairs-in-an-array
2280-count-good-triplets-in-an-array
2358-number-of-ways-to-split-array
2465-shifting-letters-ii
2478-longest-nice-subarray
2488-divide-intervals-into-minimum-number-of-groups
2527-count-subarrays-with-fixed-bounds
2533-bitwise-xor-of-all-pairings
2545-height-of-binary-tree-after-subtree-removal-queries
2551-apply-operations-to-an-array
2552-maximum-sum-of-distinct-subarrays-with-length-k
2554-minimum-total-distance-traveled
2581-divide-players-into-teams-of-equal-skill
2616-maximal-score-after-applying-k-operations
2691-count-vowel-strings-in-ranges
2699-count-the-number-of-fair-pairs
2707-merge-two-2d-arrays-by-summing-values
2792-neighboring-bitwise-xor
2794-maximum-number-of-moves-in-a-grid
3152-maximum-value-of-an-ordered-triplet-ii
3154-maximum-value-of-an-ordered-triplet-i
3227-find-missing-and-repeated-values
3309-count-prefix-and-suffix-pairs-i
3501-delete-nodes-from-linked-list-present-in-array
3656-minimum-number-of-operations-to-make-elements-in-array-distinct

Hash Table

0003-longest-substring-without-repeating-characters
0169-majority-element
0229-majority-element-ii
0496-next-greater-element-i
0567-permutation-in-string
0632-smallest-range-covering-elements-from-k-lists
0870-magic-squares-in-grid
0952-word-subsets
0999-regions-cut-by-slashes
1256-rank-transform-of-an-array
1694-make-sum-divisible-by-p
1786-count-the-number-of-consistent-strings
2054-the-number-of-the-smallest-unoccupied-chair
2059-unique-length-3-palindromic-subsequences
2163-kth-distinct-string-in-an-array
2552-maximum-sum-of-distinct-subarrays-with-length-k
2581-divide-players-into-teams-of-equal-skill
2677-cousins-in-binary-tree-ii
2707-merge-two-2d-arrays-by-summing-values
3227-find-missing-and-repeated-values
3276-minimum-number-of-pushes-to-type-word-ii
3501-delete-nodes-from-linked-list-present-in-array
3656-minimum-number-of-operations-to-make-elements-in-array-distinct

Stack

0145-binary-tree-postorder-traversal
0496-next-greater-element-i
0503-next-greater-element-ii
0776-n-ary-tree-postorder-traversal
0957-minimum-add-to-make-parentheses-valid
1002-maximum-width-ramp
1197-parsing-a-boolean-expression
1497-design-a-stack-with-increment-operation
2095-minimum-number-of-swaps-to-make-the-string-balanced
2800-minimum-string-length-after-removing-substrings

Monotonic Stack

0496-next-greater-element-i
0503-next-greater-element-ii
1002-maximum-width-ramp

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0151-reverse-words-in-a-string
0273-integer-to-english-words
0567-permutation-in-string
0952-word-subsets
0957-minimum-add-to-make-parentheses-valid
1197-parsing-a-boolean-expression
1250-longest-common-subsequence
1304-longest-happy-string
1350-remove-sub-folders-from-the-filesystem
1524-string-matching-in-an-array
1537-maximum-score-after-splitting-a-string
1667-find-kth-bit-in-nth-binary-string
1786-count-the-number-of-consistent-strings
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
1923-sentence-similarity-iii
2059-unique-length-3-palindromic-subsequences
2076-sum-of-digits-of-string-after-convert
2095-minimum-number-of-swaps-to-make-the-string-balanced
2163-kth-distinct-string-in-an-array
2463-minimum-recolors-to-get-k-consecutive-black-blocks
2465-shifting-letters-ii
2691-count-vowel-strings-in-ranges
2800-minimum-string-length-after-removing-substrings
3195-separate-black-and-white-balls
3276-minimum-number-of-pushes-to-type-word-ii
3309-count-prefix-and-suffix-pairs-i

Counting

0169-majority-element
0229-majority-element-ii
1396-count-servers-that-communicate
1786-count-the-number-of-consistent-strings
2163-kth-distinct-string-in-an-array
3276-minimum-number-of-pushes-to-type-word-ii

Greedy

0624-maximum-distance-in-arrays
0632-smallest-range-covering-elements-from-k-lists
0670-maximum-swap
0890-lemonade-change
0957-minimum-add-to-make-parentheses-valid
1304-longest-happy-string
2095-minimum-number-of-swaps-to-make-the-string-balanced
2488-divide-intervals-into-minimum-number-of-groups
2616-maximal-score-after-applying-k-operations
3195-separate-black-and-white-balls
3276-minimum-number-of-pushes-to-type-word-ii

Sorting

0015-3sum
0056-merge-intervals
0075-sort-colors
0088-merge-sorted-array
0169-majority-element
0215-kth-largest-element-in-an-array
0229-majority-element-ii
0368-largest-divisible-subset
0632-smallest-range-covering-elements-from-k-lists
0719-find-k-th-smallest-pair-distance
1256-rank-transform-of-an-array
2488-divide-intervals-into-minimum-number-of-groups
2554-minimum-total-distance-traveled
2581-divide-players-into-teams-of-equal-skill
2646-kth-largest-sum-in-a-binary-tree
2699-count-the-number-of-fair-pairs
3276-minimum-number-of-pushes-to-type-word-ii

Divide and Conquer

0053-maximum-subarray
0169-majority-element
0215-kth-largest-element-in-an-array
2280-count-good-triplets-in-an-array

Dynamic Programming

0005-longest-palindromic-substring
0053-maximum-subarray
0062-unique-paths
0064-minimum-path-sum
0118-pascals-triangle
0121-best-time-to-buy-and-sell-stock
0300-longest-increasing-subsequence
0368-largest-divisible-subset
0416-partition-equal-subset-sum
1240-stone-game-ii
1250-longest-common-subsequence
1402-count-square-submatrices-with-all-ones
2262-solving-questions-with-brainpower
2554-minimum-total-distance-traveled
2794-maximum-number-of-moves-in-a-grid

Two Pointers

0005-longest-palindromic-substring
0015-3sum
0031-next-permutation
0075-sort-colors
0088-merge-sorted-array
0151-reverse-words-in-a-string
0287-find-the-duplicate-number
0567-permutation-in-string
0719-find-k-th-smallest-pair-distance
0908-middle-of-the-linked-list
1923-sentence-similarity-iii
2095-minimum-number-of-swaps-to-make-the-string-balanced
2265-partition-array-according-to-given-pivot
2488-divide-intervals-into-minimum-number-of-groups
2551-apply-operations-to-an-array
2581-divide-players-into-teams-of-equal-skill
2699-count-the-number-of-fair-pairs
2707-merge-two-2d-arrays-by-summing-values
3195-separate-black-and-white-balls

Math

0048-rotate-image
0062-unique-paths
0273-integer-to-english-words
0368-largest-divisible-subset
0670-maximum-swap
0870-magic-squares-in-grid
1240-stone-game-ii
1889-check-if-number-is-a-sum-of-powers-of-three
1993-sum-of-all-subset-xor-totals
2050-count-good-numbers
2155-find-missing-observations
2610-closest-prime-numbers-in-range
2649-count-total-number-of-colored-cells
2998-count-symmetric-integers
3227-find-missing-and-repeated-values

Recursion

0273-integer-to-english-words
1197-parsing-a-boolean-expression
1667-find-kth-bit-in-nth-binary-string
2050-count-good-numbers

Matrix

0048-rotate-image
0064-minimum-path-sum
0074-search-a-2d-matrix
0870-magic-squares-in-grid
0921-spiral-matrix-iii
0999-regions-cut-by-slashes
1396-count-servers-that-communicate
1402-count-square-submatrices-with-all-ones
1691-minimum-number-of-days-to-disconnect-island
2794-maximum-number-of-moves-in-a-grid
3227-find-missing-and-repeated-values

Simulation

0921-spiral-matrix-iii
1667-find-kth-bit-in-nth-binary-string
2006-find-the-student-that-will-replace-the-chalk
2076-sum-of-digits-of-string-after-convert
2155-find-missing-observations
2265-partition-array-according-to-given-pivot
2551-apply-operations-to-an-array
2800-minimum-string-length-after-removing-substrings

Depth-First Search

0145-binary-tree-postorder-traversal
0776-n-ary-tree-postorder-traversal
0999-regions-cut-by-slashes
1350-remove-sub-folders-from-the-filesystem
1396-count-servers-that-communicate
1691-minimum-number-of-days-to-disconnect-island
2545-height-of-binary-tree-after-subtree-removal-queries
2677-cousins-in-binary-tree-ii

Breadth-First Search

0999-regions-cut-by-slashes
1396-count-servers-that-communicate
1691-minimum-number-of-days-to-disconnect-island
2545-height-of-binary-tree-after-subtree-removal-queries
2646-kth-largest-sum-in-a-binary-tree
2677-cousins-in-binary-tree-ii

Union Find

0999-regions-cut-by-slashes
1396-count-servers-that-communicate

Strongly Connected Component

1691-minimum-number-of-days-to-disconnect-island

Tree

0145-binary-tree-postorder-traversal
0776-n-ary-tree-postorder-traversal
0789-kth-largest-element-in-a-stream
2545-height-of-binary-tree-after-subtree-removal-queries
2646-kth-largest-sum-in-a-binary-tree
2677-cousins-in-binary-tree-ii

Design

0789-kth-largest-element-in-a-stream
0859-design-circular-deque
1497-design-a-stack-with-increment-operation

Binary Search Tree

0074-search-a-2d-matrix
0287-find-the-duplicate-number
0300-longest-increasing-subsequence
0719-find-k-th-smallest-pair-distance
0789-kth-largest-element-in-a-stream
2006-find-the-student-that-will-replace-the-chalk
2280-count-good-triplets-in-an-array
2699-count-the-number-of-fair-pairs

Heap (Priority Queue)

0215-kth-largest-element-in-an-array
0632-smallest-range-covering-elements-from-k-lists
0789-kth-largest-element-in-a-stream
1304-longest-happy-string
2054-the-number-of-the-smallest-unoccupied-chair
2488-divide-intervals-into-minimum-number-of-groups
2616-maximal-score-after-applying-k-operations

Binary Tree

0145-binary-tree-postorder-traversal
0789-kth-largest-element-in-a-stream
2545-height-of-binary-tree-after-subtree-removal-queries
2646-kth-largest-sum-in-a-binary-tree
2677-cousins-in-binary-tree-ii

Data Stream

0789-kth-largest-element-in-a-stream

Prefix Sum

1240-stone-game-ii
1537-maximum-score-after-splitting-a-string
1694-make-sum-divisible-by-p
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
2006-find-the-student-that-will-replace-the-chalk
2059-unique-length-3-palindromic-subsequences
2358-number-of-ways-to-split-array
2465-shifting-letters-ii
2488-divide-intervals-into-minimum-number-of-groups
2691-count-vowel-strings-in-ranges

Game Theory

1240-stone-game-ii

Bit Manipulation

0078-subsets
0090-subsets-ii
0287-find-the-duplicate-number
0476-number-complement
1786-count-the-number-of-consistent-strings
1993-sum-of-all-subset-xor-totals
2059-unique-length-3-palindromic-subsequences
2170-count-number-of-maximum-bitwise-or-subsets
2478-longest-nice-subarray
2533-bitwise-xor-of-all-pairings
2792-neighboring-bitwise-xor

Linked List

0859-design-circular-deque
0908-middle-of-the-linked-list
3501-delete-nodes-from-linked-list-present-in-array

Queue

0859-design-circular-deque
2527-count-subarrays-with-fixed-bounds

Sliding Window

0003-longest-substring-without-repeating-characters
0567-permutation-in-string
0632-smallest-range-covering-elements-from-k-lists
2463-minimum-recolors-to-get-k-consecutive-black-blocks
2478-longest-nice-subarray
2527-count-subarrays-with-fixed-bounds
2552-maximum-sum-of-distinct-subarrays-with-length-k

Combinatorics

0062-unique-paths
1993-sum-of-all-subset-xor-totals

Quickselect

0215-kth-largest-element-in-an-array

Backtracking

0046-permutations
0051-n-queens
0078-subsets
0090-subsets-ii
1993-sum-of-all-subset-xor-totals
2170-count-number-of-maximum-bitwise-or-subsets

Enumeration

1656-count-good-triplets
1993-sum-of-all-subset-xor-totals
2170-count-number-of-maximum-bitwise-or-subsets
2998-count-symmetric-integers

Trie

1350-remove-sub-folders-from-the-filesystem
3309-count-prefix-and-suffix-pairs-i

String Matching

1524-string-matching-in-an-array
3309-count-prefix-and-suffix-pairs-i

Rolling Hash

3309-count-prefix-and-suffix-pairs-i

Hash Function

3309-count-prefix-and-suffix-pairs-i

Brainteaser

2533-bitwise-xor-of-all-pairings

Number Theory

2610-closest-prime-numbers-in-range

Binary Indexed Tree

2280-count-good-triplets-in-an-array

Segment Tree

2280-count-good-triplets-in-an-array

Merge Sort

2280-count-good-triplets-in-an-array

Ordered Set

2280-count-good-triplets-in-an-array

Monotonic Queue

2527-count-subarrays-with-fixed-bounds