Added tasks 124-138

Author: javadev

README.md

@@ -560,6 +560,7 @@
 
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+| 0138 |[Copy List with Random Pointer](src/main/erlang/g0101_0200/s0138_copy_list_with_random_pointer)| Medium | Array, Bit_Manipulation | 6 | 100.00
 
 #### Day 15
 
@@ -916,6 +917,7 @@
 
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+| 0136 |[Single Number](src/main/erlang/g0101_0200/s0136_single_number)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
 | 0007 |[Reverse Integer](src/main/erlang/g0001_0100/s0007_reverse_integer)| Medium | Top_Interview_Questions, Math | 244 | 100.00
 | 0009 |[Palindrome Number](src/main/erlang/g0001_0100/s0009_palindrome_number)| Easy | Math | 1 | 100.00
 
@@ -974,6 +976,7 @@
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 | 0024 |[Swap Nodes in Pairs](src/main/erlang/g0001_0100/s0024_swap_nodes_in_pairs)| Medium | Top_100_Liked_Questions, Linked_List, Recursion, Big_O_Time_O(n)_Space_O(1) | 0 | 100.00
 | 0021 |[Merge Two Sorted Lists](src/main/erlang/g0001_0100/s0021_merge_two_sorted_lists)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Linked_List, Recursion, Big_O_Time_O(m+n)_Space_O(m+n) | 0 | 100.00
+| 0138 |[Copy List with Random Pointer](src/main/erlang/g0101_0200/s0138_copy_list_with_random_pointer)| Medium | Array, Bit_Manipulation | 6 | 100.00
 
 #### Udemy Tree Stack Queue
 
@@ -982,6 +985,7 @@
 | 0094 |[Binary Tree Inorder Traversal](src/main/erlang/g0001_0100/s0094_binary_tree_inorder_traversal)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Tree, Binary_Tree, Stack, Big_O_Time_O(n)_Space_O(n) | 0 | 100.00
 | 0102 |[Binary Tree Level Order Traversal](src/main/erlang/g0101_0200/s0102_binary_tree_level_order_traversal)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(N) | 12 | 100.00
 | 0104 |[Maximum Depth of Binary Tree](src/main/erlang/g0101_0200/s0104_maximum_depth_of_binary_tree)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(H) | 0 | 100.00
+| 0124 |[Binary Tree Maximum Path Sum](src/main/erlang/g0101_0200/s0124_binary_tree_maximum_path_sum)| Hard | Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Depth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(N) | 4 | 100.00
 | 0098 |[Validate Binary Search Tree](src/main/erlang/g0001_0100/s0098_validate_binary_search_tree)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Tree, Binary_Tree, Binary_Search_Tree, Big_O_Time_O(N)_Space_O(log(N)) | 0 | 100.00
 
 #### Udemy Trie and Heap
@@ -1111,6 +1115,7 @@
 
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+| 0136 |[Single Number](src/main/erlang/g0101_0200/s0136_single_number)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
 | 0015 |[3Sum](src/main/erlang/g0001_0100/s0015_3sum)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n\*log(n))_Space_O(n^2) | 1387 | 100.00
 
 #### Day 2 Array
@@ -1298,6 +1303,7 @@
 
 | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
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+| 0136 |[Single Number](src/main/erlang/g0101_0200/s0136_single_number)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
 
 ## Algorithms
 
@@ -1307,6 +1313,11 @@
 | 0739 |[Daily Temperatures](src/main/erlang/g0701_0800/s0739_daily_temperatures)| Medium | Top_100_Liked_Questions, Array, Stack, Monotonic_Stack, Programming_Skills_II_Day_6, Big_O_Time_O(n)_Space_O(n) | 94 | 100.00
 | 0647 |[Palindromic Substrings](src/main/erlang/g0601_0700/s0647_palindromic_substrings)| Medium | String, Dynamic_Programming, Big_O_Time_O(n^2)_Space_O(n) | 17 | 100.00
 | 0560 |[Subarray Sum Equals K](src/main/erlang/g0501_0600/s0560_subarray_sum_equals_k)| Medium | Top_100_Liked_Questions, Array, Hash_Table, Prefix_Sum, Data_Structure_II_Day_5_Array, Big_O_Time_O(n)_Space_O(n) | 47 | 100.00
+| 0138 |[Copy List with Random Pointer](src/main/erlang/g0101_0200/s0138_copy_list_with_random_pointer)| Medium | Array, Bit_Manipulation | 6 | 100.00
+| 0136 |[Single Number](src/main/erlang/g0101_0200/s0136_single_number)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Data_Structure_II_Day_1_Array, Algorithm_I_Day_14_Bit_Manipulation, Udemy_Integers, Big_O_Time_O(N)_Space_O(1) | 0 | 100.00
+| 0131 |[Palindrome Partitioning](src/main/erlang/g0101_0200/s0131_palindrome_partitioning)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, String, Dynamic_Programming, Backtracking, Big_O_Time_O(N\*2^N)_Space_O(2^N\*N) | 24 | 100.00
+| 0128 |[Longest Consecutive Sequence](src/main/erlang/g0101_0200/s0128_longest_consecutive_sequence)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Union_Find, Big_O_Time_O(N_log_N)_Space_O(1) | 42 | 100.00
+| 0124 |[Binary Tree Maximum Path Sum](src/main/erlang/g0101_0200/s0124_binary_tree_maximum_path_sum)| Hard | Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Depth_First_Search, Tree, Binary_Tree, Udemy_Tree_Stack_Queue, Big_O_Time_O(N)_Space_O(N) | 4 | 100.00
 | 0121 |[Best Time to Buy and Sell Stock](src/main/erlang/g0101_0200/s0121_best_time_to_buy_and_sell_stock)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Data_Structure_I_Day_3_Array, Dynamic_Programming_I_Day_7, Level_1_Day_5_Greedy, Udemy_Arrays, Big_O_Time_O(N)_Space_O(1) | 89 | 100.00
 | 0105 |[Construct Binary Tree from Preorder and Inorder Traversal](src/main/erlang/g0101_0200/s0105_construct_binary_tree_from_preorder_and_inorder_traversal)| Medium | Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Tree, Binary_Tree, Divide_and_Conquer, Data_Structure_II_Day_15_Tree, Big_O_Time_O(N)_Space_O(N) | 169 | 100.00
 | 0104 |[Maximum Depth of Binary Tree](src/main/erlang/g0101_0200/s0104_maximum_depth_of_binary_tree)| Easy | Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Data_Structure_I_Day_11_Tree, Programming_Skills_I_Day_10_Linked_List_and_Tree, Udemy_Tree_Stack_Queue, Big_O_Time_O(N)_Space_O(H) | 0 | 100.00

src/main/erlang/g0101_0200/s0124_binary_tree_maximum_path_sum/readme.md

@@ -0,0 +1,63 @@
+[![](https://img.shields.io/github/stars/LeetCode-in-Erlang/LeetCode-in-Erlang?label=Stars&style=flat-square)](https://github.com/LeetCode-in-Erlang/LeetCode-in-Erlang)
+[![](https://img.shields.io/github/forks/LeetCode-in-Erlang/LeetCode-in-Erlang?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/LeetCode-in-Erlang/LeetCode-in-Erlang/fork)
+
+## 124\. Binary Tree Maximum Path Sum
+
+Hard
+
+A **path** in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecting them. A node can only appear in the sequence **at most once**. Note that the path does not need to pass through the root.
+
+The **path sum** of a path is the sum of the node's values in the path.
+
+Given the `root` of a binary tree, return _the maximum **path sum** of any **non-empty** path_.
+
+**Example 1:**
+
+![](https://assets.leetcode.com/uploads/2020/10/13/exx1.jpg)
+
+**Input:** root = [1,2,3]
+
+**Output:** 6
+
+**Explanation:** The optimal path is 2 -> 1 -> 3 with a path sum of 2 + 1 + 3 = 6.
+
+**Example 2:**
+
+![](https://assets.leetcode.com/uploads/2020/10/13/exx2.jpg)
+
+**Input:** root = [-10,9,20,null,null,15,7]
+
+**Output:** 42
+
+**Explanation:** The optimal path is 15 -> 20 -> 7 with a path sum of 15 + 20 + 7 = 42.
+
+**Constraints:**
+
+*   The number of nodes in the tree is in the range <code>[1, 3 * 10<sup>4</sup>]</code>.
+*   `-1000 <= Node.val <= 1000`
+
+## Solution
+
+```erlang
+%% Definition for a binary tree node.
+%%
+%% -record(tree_node, {val = 0 :: integer(),
+%%                     left = null  :: 'null' | #tree_node{},
+%%                     right = null :: 'null' | #tree_node{}}).
+
+-spec max_path_sum(Root :: #tree_node{} | null) -> integer().
+max_path_sum(#tree_node{val = Val, left = null, right = null}) ->
+    Val;
+max_path_sum(Root) ->
+    element(2, max_path(Root, -1001)).
+
+-spec max_path(Node :: #tree_node{} | null, Max :: integer()) -> {integer(), integer()}.
+max_path(null, Max) ->
+    {0, Max};
+max_path(#tree_node{val = Val, left = Left, right = Right}, Max) ->
+    {LVal, LMax} = max_path(Left, Max),
+    {RVal, RMax} = max_path(Right, Max),
+    LocalMax = lists:max([LVal + Val, RVal + Val, Val]),
+    GlobalMax = lists:max([Max, Val, Val + LVal, Val + RVal, Val + LVal + RVal, LMax, RMax]),
+    {LocalMax, GlobalMax}.
+```

src/main/erlang/g0101_0200/s0128_longest_consecutive_sequence/readme.md

@@ -0,0 +1,52 @@
+[![](https://img.shields.io/github/stars/LeetCode-in-Erlang/LeetCode-in-Erlang?label=Stars&style=flat-square)](https://github.com/LeetCode-in-Erlang/LeetCode-in-Erlang)
+[![](https://img.shields.io/github/forks/LeetCode-in-Erlang/LeetCode-in-Erlang?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/LeetCode-in-Erlang/LeetCode-in-Erlang/fork)
+
+## 128\. Longest Consecutive Sequence
+
+Medium
+
+Given an unsorted array of integers `nums`, return _the length of the longest consecutive elements sequence._
+
+You must write an algorithm that runs in `O(n)` time.
+
+**Example 1:**
+
+**Input:** nums = [100,4,200,1,3,2]
+
+**Output:** 4
+
+**Explanation:** The longest consecutive elements sequence is `[1, 2, 3, 4]`. Therefore its length is 4.
+
+**Example 2:**
+
+**Input:** nums = [0,3,7,2,5,8,4,6,0,1]
+
+**Output:** 9
+
+**Constraints:**
+
+*   <code>0 <= nums.length <= 10<sup>5</sup></code>
+*   <code>-10<sup>9</sup> <= nums[i] <= 10<sup>9</sup></code>
+
+## Solution
+
+```erlang
+-spec longest_consecutive(Nums :: [integer()]) -> integer().
+longest_consecutive(Nums) ->
+    Sorted = lists:sort(Nums),
+    SeqLens = count_consecutive(Sorted, [1]),
+    lists:max(SeqLens).
+
+-spec count_consecutive(Nums :: [integer()], SeqLens :: [integer()]) -> [integer()].
+count_consecutive([H1, H2 | Tail], [SeqHead | SeqTail]) ->
+    NewLen = case H1 - H2 of
+        -1 -> SeqHead + 1; % Consecutive elements
+         0 -> SeqHead;     % Same element, do nothing
+         _ -> 1            % Not consecutive, reset count
+    end,
+    count_consecutive([H2 | Tail], [NewLen | [SeqHead | SeqTail]]);
+count_consecutive([_], SeqLens) ->
+    SeqLens; % End of list with remaining sequence lengths
+count_consecutive([], [_]) ->
+    [0]. % Single number case
+```

src/main/erlang/g0101_0200/s0131_palindrome_partitioning/readme.md

@@ -0,0 +1,61 @@
+[![](https://img.shields.io/github/stars/LeetCode-in-Erlang/LeetCode-in-Erlang?label=Stars&style=flat-square)](https://github.com/LeetCode-in-Erlang/LeetCode-in-Erlang)
+[![](https://img.shields.io/github/forks/LeetCode-in-Erlang/LeetCode-in-Erlang?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/LeetCode-in-Erlang/LeetCode-in-Erlang/fork)
+
+## 131\. Palindrome Partitioning
+
+Medium
+
+Given a string `s`, partition `s` such that every substring of the partition is a **palindrome**. Return all possible palindrome partitioning of `s`.
+
+A **palindrome** string is a string that reads the same backward as forward.
+
+**Example 1:**
+
+**Input:** s = "aab"
+
+**Output:** [["a","a","b"],["aa","b"]]
+
+**Example 2:**
+
+**Input:** s = "a"
+
+**Output:** [["a"]]
+
+**Constraints:**
+
+*   `1 <= s.length <= 16`
+*   `s` contains only lowercase English letters.
+
+## Solution
+
+```erlang
+-spec partition(S :: unicode:unicode_binary()) -> [[unicode:unicode_binary()]].
+partition(S) ->
+    Len = byte_size(S),
+    dfs(S, Len, 0, [], []).
+
+% Base case: when we've processed the entire string
+dfs(_S, Len, L, Subs, Ans) when L =:= Len ->
+    [lists:reverse(Subs) | Ans];
+
+% Recursive case: try all possible partitions
+dfs(S, Len, L, Subs, Ans) ->
+    partition_from_position(S, Len, L, L, Subs, Ans).
+
+partition_from_position(S, Len, L, R, Subs, Ans) when R < Len ->
+    Substring = binary:part(S, L, R - L + 1),
+    NewAns = case is_palindrome(Substring) of
+        true -> 
+            dfs(S, Len, R + 1, [Substring | Subs], Ans);
+        false -> 
+            Ans
+    end,
+    partition_from_position(S, Len, L, R + 1, Subs, NewAns);
+partition_from_position(_S, _Len, _L, _R, _Subs, Ans) ->
+    Ans.
+
+% Helper function to check if a binary is a palindrome
+is_palindrome(Bin) ->
+    List = binary_to_list(Bin),
+    List =:= lists:reverse(List).
+```

src/main/erlang/g0101_0200/s0136_single_number/readme.md

@@ -0,0 +1,43 @@
+[![](https://img.shields.io/github/stars/LeetCode-in-Erlang/LeetCode-in-Erlang?label=Stars&style=flat-square)](https://github.com/LeetCode-in-Erlang/LeetCode-in-Erlang)
+[![](https://img.shields.io/github/forks/LeetCode-in-Erlang/LeetCode-in-Erlang?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/LeetCode-in-Erlang/LeetCode-in-Erlang/fork)
+
+## 136\. Single Number
+
+Easy
+
+Given a **non-empty** array of integers `nums`, every element appears _twice_ except for one. Find that single one.
+
+You must implement a solution with a linear runtime complexity and use only constant extra space.
+
+**Example 1:**
+
+**Input:** nums = [2,2,1]
+
+**Output:** 1
+
+**Example 2:**
+
+**Input:** nums = [4,1,2,1,2]
+
+**Output:** 4
+
+**Example 3:**
+
+**Input:** nums = [1]
+
+**Output:** 1
+
+**Constraints:**
+
+*   <code>1 <= nums.length <= 3 * 10<sup>4</sup></code>
+*   <code>-3 * 10<sup>4</sup> <= nums[i] <= 3 * 10<sup>4</sup></code>
+*   Each element in the array appears twice except for one element which appears only once.
+
+## Solution
+
+```erlang
+-spec single_number(Nums :: [integer()]) -> integer().
+single_number(Nums) ->
+    %% using lists:foldl to calculate the xor of all elements in the list
+    lists:foldl(fun(X, Acc) -> X bxor Acc end, 0, Nums).
+```

src/main/erlang/g0101_0200/s0138_copy_list_with_random_pointer/readme.md

@@ -0,0 +1,65 @@
+[![](https://img.shields.io/github/stars/LeetCode-in-Erlang/LeetCode-in-Erlang?label=Stars&style=flat-square)](https://github.com/LeetCode-in-Erlang/LeetCode-in-Erlang)
+[![](https://img.shields.io/github/forks/LeetCode-in-Erlang/LeetCode-in-Erlang?label=Fork%20me%20on%20GitHub%20&style=flat-square)](https://github.com/LeetCode-in-Erlang/LeetCode-in-Erlang/fork)
+
+## 138\. Copy List with Random Pointer
+
+Medium
+
+A linked list of length `n` is given such that each node contains an additional random pointer, which could point to any node in the list, or `null`.
+
+Construct a [**deep copy**](https://en.wikipedia.org/wiki/Object_copying#Deep_copy) of the list. The deep copy should consist of exactly `n` **brand new** nodes, where each new node has its value set to the value of its corresponding original node. Both the `next` and `random` pointer of the new nodes should point to new nodes in the copied list such that the pointers in the original list and copied list represent the same list state. **None of the pointers in the new list should point to nodes in the original list**.
+
+For example, if there are two nodes `X` and `Y` in the original list, where `X.random --> Y`, then for the corresponding two nodes `x` and `y` in the copied list, `x.random --> y`.
+
+Return _the head of the copied linked list_.
+
+The linked list is represented in the input/output as a list of `n` nodes. Each node is represented as a pair of `[val, random_index]` where:
+
+*   `val`: an integer representing `Node.val`
+*   `random_index`: the index of the node (range from `0` to `n-1`) that the `random` pointer points to, or `null` if it does not point to any node.
+
+Your code will **only** be given the `head` of the original linked list.
+
+**Example 1:**
+
+![](https://assets.leetcode.com/uploads/2019/12/18/e1.png)
+
+**Input:** head = \[\[7,null],[13,0],[11,4],[10,2],[1,0]]
+
+**Output:** [[7,null],[13,0],[11,4],[10,2],[1,0]]
+
+**Example 2:**
+
+![](https://assets.leetcode.com/uploads/2019/12/18/e2.png)
+
+**Input:** head = \[\[1,1],[2,1]]
+
+**Output:** [[1,1],[2,1]]
+
+**Example 3:**
+
+**![](https://assets.leetcode.com/uploads/2019/12/18/e3.png)**
+
+**Input:** head = \[\[3,null],[3,0],[3,null]]
+
+**Output:** [[3,null],[3,0],[3,null]]
+
+**Constraints:**
+
+*   `0 <= n <= 1000`
+*   <code>-10<sup>4</sup> <= Node.val <= 10<sup>4</sup></code>
+*   `Node.random` is `null` or is pointing to some node in the linked list.
+
+## Solution
+
+```erlang
+-spec single_number(Nums :: [integer()]) -> integer().
+single_number(Nums) ->
+    Frequencies = lists:foldl(fun count_frequency/2, #{}, Nums),
+    {Key, _} = lists:keyfind(1, 2, maps:to_list(Frequencies)),
+    Key.
+
+-spec count_frequency(Num :: integer(), Map :: map()) -> map().
+count_frequency(Num, Map) ->
+    maps:update_with(Num, fun(V) -> V + 1 end, 1, Map).
+```