摘要： Given an array nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k num 阅读全文

摘要： Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST. Calling next() will return the n 阅读全文

摘要： Given n nodes labeled from 0 to n-1 and a list of undirected edges (each edge is a pair of nodes), write a function to check whether these edges make 阅读全文

摘要： Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n. 1. DP Set an array, first 阅读全文

摘要： Remove the minimum number of invalid parentheses in order to make the input string valid. Return all possible results. Note: The input string may cont 阅读全文

摘要： There are a total of n courses you have to take, labeled from 0 to n-1. Some courses may have prerequisites, for example to take course 0 you have to 阅读全文

摘要： Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacen 阅读全文

摘要： There are n cities connected by m flights. Each fight starts from city u and arrives at v with a price w. Now given all the cities and fights, togethe 阅读全文

摘要： Given two words (beginWord and endWord), and a dictionary's word list, find the length of shortest transformation sequence from beginWord to endWord, 阅读全文

摘要： There are two sorted arrays nums1 and nums2 of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity sh 阅读全文