James Pan

原题网址：https://leetcode.com/problems/find-the-duplicate-number/ Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate nu

原题网址：https://leetcode.com/problems/linked-list-cycle-ii/ Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Note: Do not modify the linked list.

原题网址：https://leetcode.com/problems/linked-list-cycle/ Given a linked list, determine if it has a cycle in it. Follow up: Can you solve it without using extra space? 方法：使用两个指针。 /** * Defini

原题网址：https://leetcode.com/problems/happy-number/ Write an algorithm to determine if a number is "happy". A happy number is a number defined by the following process: Starting with any positive

原题网址：https://leetcode.com/problems/first-missing-positive/ Given an unsorted integer array, find the first missing positive integer. For example, Given [1,2,0] return 3, and [3,4,-1,1] retur

原题网址：https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/ Given an array of integers where 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.