Create 560. Subarray Sum Equals K.cpp

Author: fengvyi

Diff for: C++/560. Subarray Sum Equals K.cpp

@@ -0,0 +1,14 @@
+class Solution {
+public:
+    int subarraySum(vector<int>& nums, int k) {
+        int count = 0;
+        unordered_map<int, int>m;
+        int sum = 0;
+        for(auto x: nums){
+            m[sum]++;
+            sum += x;
+            if(m.count(sum - k) > 0) count += m[sum - k];
+        }
+        return count;
+    }
+};