Leetcode 560. And is the prefix and of the subarray of K

Original link ：Leetcode 560. And for K Subarray

class Solution {
    
public:
    int subarraySum(vector<int>& nums, int k) {
    
        int n=nums.size(),res=0,tmp=0;
        unordered_map<int,int> mp;
        mp[0]=1;
        for(int i=0;i<n;i++)
        {
    
            tmp+=nums[i];
            if(mp.count(tmp-k)) res+=mp[tmp-k];
            mp[tmp]++;
        }
        return res;
    }
};