GeeksforGeeks -Largest subarray with 0 sum- GoldmanSachs - Easy

 int maxLen(vector<int>&A, int n){   
        unordered_map<int, int> kow;
        int maxsum = 0;
        int sum = 0;
        for(int i = 0; i < n; i++){
            sum += A[i];
        if(sum == 0){
            maxsum = i + 1;
        }else{
            if(kow.find(sum) != kow.end()){
                maxsum = max(maxsum, i - kow[sum]);
            }else{
                kow[sum] = i;
            }
        }
        }
        return maxsum;
    }