217. Contains Duplicate

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.

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此题应有很多种方法，不乏开辟空间减少时间消耗，或者先排序再判断减少空间消耗，当然也有一种只有一行的的set方法比较新颖：

#include <set>using namespace std;class Solution {public:    bool containsDuplicate(vector<int>& nums) {        return nums.size() > set<int>(nums.begin(), nums.end()).size();            }};