原文链接: https://leetcode-cn.com/problems/insert-into-a-binary-search-tree 英文原文You are given the root node of a binary search tree (BST) and a value to insert into the tree. Return the root node of the BST after the insertion. It is guaranteed that the …

原文链接: https://leetcode-cn.com/problems/sliding-puzzle 英文原文On an 2 x 3 board, there are five tiles labeled from 1 to 5, and an empty square represented by 0. A move consists of choosing 0 and a 4-directionally adjacent number and swapping it. The stat…

原文链接: https://leetcode-cn.com/problems/kth-largest-element-in-a-stream 英文原文Design a class to find the kth largest element in a stream. Note that it is the kth largest element in the sorted order, not the kth distinct element. Implement KthLargest cla…

原文链接: https://leetcode-cn.com/problems/global-and-local-inversions 英文原文You are given an integer array nums of length n which represents a permutation of all the integers in the range [0, n - 1]. The number of global inversions is the number of the di…

原文链接: https://leetcode-cn.com/problems/binary-search 英文原文Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return …

原文链接: https://leetcode-cn.com/problems/swap-adjacent-in-lr-string 英文原文In a string composed of 'L', 'R', and 'X' characters, like "RXXLRXRXL", a move consists of either replacing one occurrence of "XL" with "LX", or replacing one occurrence of "RX" wi…

原文链接: https://leetcode-cn.com/problems/swim-in-rising-water 英文原文You are given an n x n integer matrix grid where each value grid[i][j] represents the elevation at that point (i, j). The rain starts to fall. At time t, the depth of the water everywher…

原文链接: https://leetcode-cn.com/problems/k-th-symbol-in-grammar 英文原文We build a table of n rows (1-indexed). We start by writing 0 in the 1st row. Now in every subsequent row, we look at the previous row and replace each occurrence of 0 with 01, and eac…

原文链接: https://leetcode-cn.com/problems/reaching-points 英文原文Given four integers sx, sy, tx, and ty, return true if it is possible to convert the point (sx, sy) to the point (tx, ty) through some operations, or false otherwise. The allowed operation on…

原文链接: https://leetcode-cn.com/problems/transform-to-chessboard 英文原文You are given an n x n binary grid board. In each move, you can swap any two rows with each other, or any two columns with each other. Return the minimum number of moves to transform …

原文链接: https://leetcode-cn.com/problems/minimum-distance-between-bst-nodes 英文原文Given the root of a Binary Search Tree (BST), return the minimum difference between the values of any two different nodes in the tree. Example 1: Input: root = [4,2,6,1,3] …

原文链接: https://leetcode-cn.com/problems/letter-case-permutation 英文原文Given a string s, we can transform every letter individually to be lowercase or uppercase to create another string. Return a list of all possible strings we could create. You can retu…

原文链接: https://leetcode-cn.com/problems/is-graph-bipartite 英文原文There 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. …

原文链接: https://leetcode-cn.com/problems/k-th-smallest-prime-fraction 英文原文You are given a sorted integer array arr containing 1 and prime numbers, where all the integers of arr are unique. You are also given an integer k. For every i and j where 0 <= i…

原文链接: https://leetcode-cn.com/problems/cheapest-flights-within-k-stops 英文原文There are n cities connected by some number of flights. You are given an array flights where flights[i] = [fromi, toi, pricei] indicates that there is a flight from city fromi…

原文链接: https://leetcode-cn.com/problems/rotated-digits 英文原文An integer x is a good if after rotating each digit individually by 180 degrees, we get a valid number that is different from x. Each digit must be rotated - we cannot choose to leave it alone…

原文链接: https://leetcode-cn.com/problems/escape-the-ghosts 英文原文You are playing a simplified PAC-MAN game on an infinite 2-D grid. You start at the point [0, 0], and you are given a destination point target = [xtarget, ytarget] that you are trying to ge…

原文链接: https://leetcode-cn.com/problems/domino-and-tromino-tiling 英文原文You have two types of tiles: a 2 x 1 domino shape and a tromino shape. You may rotate these shapes. Given an integer n, return the number of ways to tile an 2 x n board. Since the a…

原文链接: https://leetcode-cn.com/problems/custom-sort-string 英文原文You are given two strings order and s. All the words of order are unique and were sorted in some custom order previously. Permute the characters of s so that they match the order that orde…

原文链接: https://leetcode-cn.com/problems/preimage-size-of-factorial-zeroes-function 英文原文Let f(x) be the number of zeroes at the end of x!. Recall that x! = 1 * 2 * 3 * ... * x and by convention, 0! = 1. For example, f(3) = 0 because 3! = 6 has no zeroe…

原文链接: https://leetcode-cn.com/problems/valid-tic-tac-toe-state 英文原文Given a Tic-Tac-Toe board as a string array board, return true if and only if it is possible to reach this board position during the course of a valid tic-tac-toe game. The board is a…

原文链接: https://leetcode-cn.com/problems/number-of-subarrays-with-bounded-maximum 英文原文Given an integer array nums and two integers left and right, return the number of contiguous non-empty subarrays such that the value of the maximum array element in t…

原文链接: https://leetcode-cn.com/problems/rotate-string 英文原文Given two strings s and goal, return true if and only if s can become goal after some number of shifts on s. A shift on s consists of moving the leftmost character of s to the rightmost positio…

原文链接: https://leetcode-cn.com/problems/smallest-rotation-with-highest-score 英文原文You are given an array nums. You can rotate it by a non-negative integer k so that the array becomes [nums[k], nums[k + 1], ... nums[nums.length - 1], nums[0], nums[1], .…

原文链接: https://leetcode-cn.com/problems/all-paths-from-source-to-target 英文原文Given a directed acyclic graph (DAG) of n nodes labeled from 0 to n - 1, find all possible paths from node 0 to node n - 1 and return them in any order. The graph is given as …

原文链接: https://leetcode-cn.com/problems/champagne-tower 英文原文We stack glasses in a pyramid, where the first row has 1 glass, the second row has 2 glasses, and so on until the 100th row. Each glass holds one cup of champagne. Then, some champagne is pou…

原文链接: https://leetcode-cn.com/problems/design-hashset 英文原文Design a HashSet without using any built-in hash table libraries. Implement MyHashSet class: void add(key) Inserts the value key into the HashSet. bool contains(key) Returns whether the value …

原文链接: https://leetcode-cn.com/problems/design-hashmap 英文原文Design a HashMap without using any built-in hash table libraries. Implement the MyHashMap class: MyHashMap() initializes the object with an empty map. void put(int key, int value) inserts a (k…

原文链接: https://leetcode-cn.com/problems/find-eventual-safe-states 英文原文There is a directed graph of n nodes with each node labeled from 0 to n - 1. The graph is represented by a 0-indexed 2D integer array graph where graph[i] is an integer array of nod…

原文链接: https://leetcode-cn.com/problems/bricks-falling-when-hit 英文原文You are given an m x n binary grid, where each 1 represents a brick and 0 represents an empty space. A brick is stable if: It is directly connected to the top of the grid, or At least…