【Leetcode】Contains Duplicate

题目链接：https://leetcode.com/problems/contains-duplicate/

题目：

Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.

思路：

1、先排序，然后判断相邻元素是否相等。时间复杂度O(nlogn)，空间复杂度O(1)

2、用hashMap。时间复杂度O(n),空间复杂度O(n)

算法：

public boolean containsDuplicate(int[] nums) {Arrays.sort(nums);for (int i = 0; i < nums.length - 1; i++) {if (nums[i] == nums[i + 1]) {return true;}}return false;}