Leetcode 存在重复

class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        set<int> duplicateSet;
        bool flag = false;
        for(auto num: nums)
        {
            if (duplicateSet.find(num) == duplicateSet.end())
            {
                duplicateSet.insert(num);
            }
            else
            {
                flag = true;
                break;
            }
        }
        return flag;
    }
};