Added tasks 121-136

Author: ThanhNIT

src/main/ts/g0101_0200/s0121_best_time_to_buy_and_sell_stock/readme.md

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+121\. Best Time to Buy and Sell Stock
+
+Easy
+
+You are given an array `prices` where `prices[i]` is the price of a given stock on the `ith` day.
+
+You want to maximize your profit by choosing a **single day** to buy one stock and choosing a **different day in the future** to sell that stock.
+
+Return _the maximum profit you can achieve from this transaction_. If you cannot achieve any profit, return `0`.
+
+**Example 1:**
+
+**Input:** prices = [7,1,5,3,6,4]
+
+**Output:** 5
+
+**Explanation:** Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5. Note that buying on day 2 and selling on day 1 is not allowed because you must buy before you sell. 
+
+**Example 2:**
+
+**Input:** prices = [7,6,4,3,1]
+
+**Output:** 0
+
+**Explanation:** In this case, no transactions are done and the max profit = 0. 
+
+**Constraints:**
+
+*   <code>1 <= prices.length <= 10<sup>5</sup></code>
+*   <code>0 <= prices[i] <= 10<sup>4</sup></code>

src/main/ts/g0101_0200/s0121_best_time_to_buy_and_sell_stock/solution.ts

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+// #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) #2023_10_05_Time_56_ms_(99.56%)_Space_52.3_MB_(13.22%)
+
+function maxProfit(prices: number[]): number {
+    let buyPrice = prices[0]
+    let maxProfit = 0
+    for (let i = 1; i < prices.length; i++) {
+        if (prices[i] < buyPrice) {
+            buyPrice = prices[i]
+        }
+        if (prices[i] - buyPrice > maxProfit) {
+            maxProfit = prices[i] - buyPrice
+        }
+    }
+    return maxProfit
+}
+
+export { maxProfit }

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

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+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`

src/main/ts/g0101_0200/s0124_binary_tree_maximum_path_sum/solution.ts

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+// #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)
+// #2023_10_05_Time_61_ms_(96.73%)_Space_51.2_MB_(97.45%)
+
+import { TreeNode } from '../../com_github_leetcode/treenode'
+
+/*
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     val: number
+ *     left: TreeNode | null
+ *     right: TreeNode | null
+ *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.left = (left===undefined ? null : left)
+ *         this.right = (right===undefined ? null : right)
+ *     }
+ * }
+ */
+function maxPathSum(root: TreeNode | null): number {
+    let max = { sum: Number.NEGATIVE_INFINITY }
+    dfs(root, max)
+    return max.sum
+}
+
+function dfs(root: TreeNode | null, max) {
+    if (root == null) {
+        return 0
+    }
+    let l = Math.max(0, dfs(root.left, max))
+    let r = Math.max(0, dfs(root.right, max))
+    max.sum = Math.max(max.sum, l + r + root.val)
+    return root.val + Math.max(l, r)
+}
+
+export { maxPathSum }

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

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+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>

src/main/ts/g0101_0200/s0128_longest_consecutive_sequence/solution.ts

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+// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #Array #Hash_Table #Union_Find
+// #Big_O_Time_O(N_log_N)_Space_O(1) #2023_10_05_Time_92_ms_(93.69%)_Space_64_MB_(30.13%)
+
+function longestConsecutive(nums: number[]): number {
+    const set = new Set(nums)
+    let max = 0
+    for (const num of nums) {
+        if (set.has(num + 1)) continue
+        let counter = 1,
+            current = num
+        while (set.has(--current)) counter++
+        max = Math.max(counter, max)
+    }
+    return max
+}
+
+export { longestConsecutive }

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

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+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.

src/main/ts/g0101_0200/s0131_palindrome_partitioning/solution.ts

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+// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #String #Dynamic_Programming
+// #Backtracking #Big_O_Time_O(N*2^N)_Space_O(2^N*N)
+// #2023_10_05_Time_203_ms_(99.22%)_Space_81.9_MB_(42.19%)
+
+function partition(s: string): string[][] {
+    const ans: string[][] = []
+    const memo = Array.from({ length: s.length }).map(() => new Array(s.length))
+    const track = (cur, start) => {
+        if (start === s.length) {
+            ans.push(cur.slice())
+            return
+        }
+        for (let i = start; i < s.length; i++) {
+            if (memo[start][i]) continue
+
+            if (isPalindrome(s, start, i, memo)) {
+                cur.push(s.substring(start, i + 1))
+                track(cur, i + 1)
+                cur.pop()
+            }
+        }
+    }
+    track([], 0)
+    return ans
+}
+
+function isPalindrome(str: string, l: number, r: number, memo: boolean[][]) {
+    while (l < r) {
+        if (str[l] !== str[r]) {
+            memo[l][r] = true
+            return false
+        }
+        l++
+        r--
+    }
+    return true
+}
+
+export { partition }

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

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+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.

src/main/ts/g0101_0200/s0136_single_number/solution.ts

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+// #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) #2023_10_05_Time_56_ms_(85.48%)_Space_45.6_MB_(63.32%)
+
+function singleNumber(nums: number[]): number {
+    let ans = 0
+    for (let num of nums) {
+        ans ^= num
+    }
+    return ans
+}
+
+export { singleNumber }