꿈꾸는공학도

https://leetcode.com/problems/pancake-sorting/description/Given an array of integers arr, sort the array by performing a series of pancake flips.In one pancake flip we do the following steps:Choose an integer k where 1 Reverse the sub-array arr[0...k-1] (0-indexed).For example, if arr = [3,2,1,4] and we performed a pancake flip choosing k = 3, we reverse the sub-array [3,2,1], so arr = [1,2,3,4]..

https://leetcode.com/problems/minesweeper/description/Let's play the minesweeper game (Wikipedia, online game)!You are given an m x n char matrix board representing the game board where:'M' represents an unrevealed mine,'E' represents an unrevealed empty square,'B' represents a revealed blank square that has no adjacent mines (i.e., above, below, left, right, and all 4 diagonals),digit ('1' to '..

https://leetcode.com/problems/next-greater-element-i/description/The next greater element of some element x in an array is the first greater element that is to the right of x in the same array.You are given two distinct 0-indexed integer arrays nums1 and nums2, where nums1 is a subset of nums2.For each 0  j such that nums1[i] == nums2[j] and determine the next greater element of nums2[j] in nums..

https://leetcode.com/problems/swap-nodes-in-pairs/description/Given a linked list, swap every two adjacent nodes and return its head. You must solve the problem without modifying the values in the list's nodes (i.e., only nodes themselves may be changed.) Example 1:Input: head = [1,2,3,4]Output: [2,1,4,3]Explanation:Example 2:Input: head = []Output: []Example 3:Input: head = [1]Output: [1]Exampl..

https://leetcode.com/problems/maximum-difference-between-node-and-ancestor/description/Given the root of a binary tree, find the maximum value v for which there exist different nodes a and b where v = |a.val - b.val| and a is an ancestor of b.A node a is an ancestor of b if either: any child of a is equal to b or any child of a is an ancestor of b. Example 1:Input: root = [8,3,10,1,6,null,14,nul..

https://leetcode.com/problems/the-k-weakest-rows-in-a-matrix/description/You are given an m x n binary matrix mat of 1's (representing soldiers) and 0's (representing civilians). The soldiers are positioned in front of the civilians. That is, all the 1's will appear to the left of all the 0's in each row.A row i is weaker than a row j if one of the following is true:The number of soldiers in row..

https://leetcode.com/problems/car-pooling/description/There is a car with capacity empty seats. The vehicle only drives east (i.e., it cannot turn around and drive west).You are given the integer capacity and an array trips where trips[i] = [numPassengersi, fromi, toi] indicates that the ith trip has numPassengersi passengers and the locations to pick them up and drop them off are fromi and toi ..

https://leetcode.com/problems/sort-characters-by-frequency/description/Given a string s, sort it in decreasing order based on the frequency of the characters. The frequency of a character is the number of times it appears in the string.Return the sorted string. If there are multiple answers, return any of them. Example 1:Input: s = "tree"Output: "eert"Explanation: 'e' appears twice while 'r' and..

https://leetcode.com/problems/trapping-rain-water/description/Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining. Example 1:Input: height = [0,1,0,2,1,0,1,3,2,1,2,1]Output: 6Explanation: The above elevation map (black section) is represented by array [0,1,0,2,1,0,1,3,2,1,2,1]. In this case, 6 units of rai..

https://leetcode.com/problems/is-graph-bipartite/description/?envType=problem-list-v2&envId=graphThere is an undirected graph with n nodes, where each node is numbered between 0 and n - 1. You are given a 2D array graph, where graph[u] is an array of nodes that node u is adjacent to. More formally, for each v in graph[u], there is an undirected edge between node u and node v. The graph has the f..