GFG PTOD | 26 Dec | Two Sum – Pair with Given Sum

 bool twoSum(vector<int>& arr, int target) {
        // code here
        std::set<int> s;
        for(int i=0; i<arr.size(); i++) {
            if(s.find(arr[i]) != s.end()) {
                return true;
            } else {
                s.insert(target-arr[i]);
            }
        }
        return false;
    }