class Solution {
public:int subarraySum(vector<int>& nums, int k) {unordered_map<int,int> mp;mp[0] = 1;int count = 0,pre = 0;for(auto x:nums){pre += x;if(mp.find(pre-k) != mp.end()){count += mp[pre-k];}mp[pre]++;}return count;}
};