226. Invert Binary Tree-翻转二叉树
Invert a binary tree. Example: Input: Output: Solution ... » 阅读全文
225. Implement Stack using Queues-用队列实现栈
Implement a last in first out (LIFO) stack using only t... » 阅读全文
219. Contains Duplicate II-存在重复元素 II
Given an array of integers and an integer k, find out w... » 阅读全文
217. Contains Duplicate-存在重复元素
Given an array of integers, find if the array contains ... » 阅读全文
205. Isomorphic Strings-同构字符串
Given two strings s and t, determine if they are isomor... » 阅读全文
204. Count Primes-计数质数
Count the number of prime numbers less than a non-negat... » 阅读全文
203. Remove Linked List Elements-移除链表元素
Remove all elements from a linked list of integers that... » 阅读全文
202. Happy Number-快乐数
Write an algorithm to determine if a number n is happy.... » 阅读全文
198. House Robber-打家劫舍
You are a professional robber planning to rob houses al... » 阅读全文
191. Number of 1 Bits-位1的个数
Write a function that takes an unsigned integer and ret... » 阅读全文