Contains Duplicate

class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {

        unordered_set<int> s;

        for(int i = 0; i<nums.size(); i++){

            if(s.find(nums[i])==s.end()){
                s.insert(nums[i]);
            }
            else{
                return true;
            }

        }

        return false;

    }
};