摘要：
Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cell, where "adjac 阅读全文
摘要：
Given a linked list, return the node where the cycle begins. If there is no cycle, return null. 此题和之前的find the duplicate number比较像，代码如下： 阅读全文
摘要：
Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space? 本题可以利用之前的find the duplicate number的方法来解， 阅读全文
摘要：
Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate number must exist. 阅读全文
摘要：
Given an array of numbers nums, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements 阅读全文