Subarray Sum Equals K

Author: TonyStark-19

Array data structure/SubarraySumEqualsK.cpp

@@ -0,0 +1,53 @@
+#include <iostream>
+#include <vector>
+#include <unordered_map>
+using namespace std;
+// Perfix sum approach
+
+int subarraySum(vector<int> &nums, int k)
+{
+    int n = nums.size();
+    int count = 0;
+    vector<int> prefixSum(n, 0);
+
+    prefixSum[0] = nums[0];
+    for (int i = 1; i < n; i++)
+    {
+        prefixSum[i] = prefixSum[i - 1] + nums[i];
+    }
+
+    unordered_map<int, int> m;
+
+    for (int j = 0; j < n; j++)
+    {
+        if (prefixSum[j] == k)
+        {
+            count++;
+        }
+
+        int val = prefixSum[j] - k;
+        if (m.find(val) != m.end())
+        {
+            count += m[val];
+        }
+
+        if (m.find(prefixSum[j]) == m.end())
+        {
+            m[prefixSum[j]] = 0;
+        }
+
+        m[prefixSum[j]]++;
+    }
+
+    return count;
+}
+
+int main()
+{
+    vector<int> arr = {9, 4, 20, 3, 10, 5};
+    int target = 33;
+
+    cout << subarraySum(arr, target) << endl;
+
+    return 0;
+}