class Solution {

public:

    bool containsDuplicate(vector<int>& nums) {

         map<int,char> exit;

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

            if(exit.find(nums[i]) == exit.end())

                 exit.insert(pair<int,char>(nums[i],1));

            else{

                   return true;

                }

            }

        return false;

    }

};