hard

ProblemGiven an integer array nums, return the length of the longest strictly increasing subsequence . Example 1: 1234Input: nums = [10,9,2,5,3,7,101,18]Output: 4Explanation: The longest increasing subsequence is [2,3,7,101], therefore the length is 4. Example 2: 123Input: nums = [0,1,0,3,2,3]Output: 4 Example 3: 123Input: nums = [7,7,7,7,7,7,7]Output: 1 Constraints: 1 <= nums.length <= 2500 104 <= nums[i] <= 104 Follow up: Can you come up with an algorithm that runs in O(n log( ...

ProblemGiven an integer array nums and an integer k, return the length of the shortest non-empty subarray of nums with a sum of at least k. If there is no such subarray, return -1. A subarray is a contiguous part of an array. Example 1: 123Input: nums = [1], k = 1Output: 1 Example 2: 123Input: nums = [1,2], k = 4Output: -1 Example 3: 123Input: nums = [2,-1,2], k = 3Output: 3 Constraints: 1 <= nums.length <= 10^5 10^5 <= nums[i] <= 10^5 1 <= k <= 10^9 Solve想破頭 簡單說就是 找到第一組解後 ...

ProblemGiven two strings s and t of lengths m and n respectively, return the minimum window substring of 1s such that every character in 1t (including duplicates) is included in the window . If there is no such substring, return the empty string 1"" . The testcases will be generated such that the answer is unique. Example 1: 1234Input: s = "ADOBECODEBANC", t = "ABC"Output: "BANC"Explanation: The minimum window substring "BANC" includes 'A ...

ProblemA 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 1234Input: root = [1,2,3]Output: 6 ...

ProblemThere are n children standing in a line. Each child is assigned a rating value given in the integer array ratings. You are giving candies to these children subjected to the following requirements: Each child must have at least one candy. Children with a higher rating get more candies than their neighbors. Return the minimum number of candies you need to have to distribute the candies to the children. Example 1: 1234Input: ratings = [1,0,2]Output: 5Explanation: You can allocate to the fi ...

ProblemGiven a string s representing a valid expression, implement a basic calculator to evaluate it, and return the result of the evaluation. Note: You are not allowed to use any built-in function which evaluates strings as mathematical expressions, such as eval(). Example 1: 123Input: s = "1 + 1"Output: 2 Example 2: 123Input: s = " 2-1 + 2 "Output: 3 Example 3: 123Input: s = "(1+(4+5+2)-3)+(6+8)"Output: 23 Constraints: 1 <= s.length <= 3 * 10^5 s consist ...

ProblemThe n-queens puzzle is the problem of placing n queens on an n x n chessboard such that no two queens attack each other. Given an integer n, return the number of distinct solutions to the n-queens puzzle. Example 1: ![(https://assets.leetcode.com/uploads/2020/11/13/queens.jpg) !https://assets.leetcode.com/uploads/2020/11/13/queens.jpg 1234Input: n = 4Output: 2Explanation: There are two distinct solutions to the 4-queens puzzle as shown. Example 2: 123Input: n = 1Output: 1 Constraints: ...

ProblemGiven an array of points where points[i] = [xi, yi] represents a point on the X-Y plane, return the maximum number of points that lie on the same straight line. Example 1: !https://assets.leetcode.com/uploads/2021/02/25/plane1.jpg 123Input: points = [[1,1],[2,2],[3,3]]Output: 3 Example 2: !https://assets.leetcode.com/uploads/2021/02/25/plane2.jpg 123Input: points = [[1,1],[3,2],[5,3],[4,1],[2,3],[1,4]]Output: 4 Constraints: 1 <= points.length <= 300 points[i].length == 2 10^4 & ...

簡易leetcode79 ProblemGiven an m x n board of characters and a list of strings words, return all words on the board. Each word must be constructed from letters of sequentially adjacent cells, where adjacent cells are horizontally or vertically neighboring. The same letter cell may not be used more than once in a word. Example 1: !https://assets.leetcode.com/uploads/2020/11/07/search1.jpg 123Input: board = [["o","a","a","n"],["e","t",&quo ...

ProblemWe can scramble a string s to get a string t using the following algorithm: If the length of the string is 1, stop. If the length of the string is > 1, do the following: Split the string into two non-empty substrings at a random index, i.e., if the string is s, divide it to x and y where s = x + y. Randomly decide to swap the two substrings or to keep them in the same order. i.e., after this step, s may become s = x + y or s = y + x. Apply step 1 recursively on each of the two substri ...