continuous-subarray-sum.cpp

class Solution {
public:
    bool checkSubarraySum(vector<int>& nums, int k) {
        unordered_map<int, int> d;
        int s =0;
        d[0]=-1;
        for(int i=0 ; i<nums.size() ; i++){
            s = (s + nums[i])%k;
            if(d.find(s) != d.end())
            {
                if(i-d[s] > 1) return true;
            }
            else d[s]=i;         
        }
        return false;
    }
};