Contains Duplicate -- leetcode

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.

基本思路：

将数字全部存入集合。最后比较集合中数的个数。

class Solution {public:    bool containsDuplicate(vector<int>& nums) {        return unordered_set<int> (nums.begin(), nums.end()).size() != nums.size();    }};