Merge pull request #38 from ankitjhagithub21/main

added the solution for potd of 15-10-2024

october_2024/potd_15_10_2024.cpp

@@ -0,0 +1,54 @@
+/*
+Example 1:
+Input: arr[] = [10, 2, -2, -20, 10] , tar = -10
+Output: 3
+Explanation: Subarrays with sum -10 are: [10, 2, -2, -20], [2, -2, -20, 10] and [-20, 10].
+
+Example 2:
+Input: arr[] = [1, 4, 20, 3, 10, 5] , tar = 33
+Output: 1
+Explanation: Subarray with sum 33 is: [20,3,10].
+
+*/
+
+#include <iostream>
+#include <unordered_map>
+#include <vector>
+
+using namespace std;
+
+int subarraySum(vector<int>& arr, int tar) {
+    // Hash map to store the cumulative sum frequencies
+    unordered_map<int, int> sum_map;
+    int current_sum = 0;
+    int count = 0;
+
+    // Initialize sum_map with sum 0 seen once (base case)
+    sum_map[0] = 1;
+
+    for (int num : arr) {
+        // Update the cumulative sum
+        current_sum += num;
+
+        // Check if there's a subarray (ending here) whose sum is target
+        if (sum_map.find(current_sum - tar) != sum_map.end()) {
+            count += sum_map[current_sum - tar];
+        }
+
+        // Add the current cumulative sum to the map
+        sum_map[current_sum]++;
+    }
+
+    return count;
+}
+
+int main() {
+    vector<int> arr = {10, 2, -2, -20, 10};
+    int tar = -10;
+
+    int result = subarraySum(arr, tar);
+    cout << "Number of subarrays with sum " << tar << ": " << result << endl;  // Output: 3
+
+    return 0;
+}
+