From 87421da8554f8750e166090681d8ad2c1ada98f8 Mon Sep 17 00:00:00 2001
From: Vipanshu Suman <73050057+vipu18@users.noreply.github.com>
Date: Thu, 2 Oct 2025 13:40:43 +0530
Subject: [PATCH] Implement subset sum problem using dynamic programming

---
 .../count_subsets_with_sum_k.cpp              | 45 +++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 CPP/dynamic-programming/count_subsets_with_sum_k.cpp

diff --git a/CPP/dynamic-programming/count_subsets_with_sum_k.cpp b/CPP/dynamic-programming/count_subsets_with_sum_k.cpp
new file mode 100644
index 0000000..10f8d17
--- /dev/null
+++ b/CPP/dynamic-programming/count_subsets_with_sum_k.cpp
@@ -0,0 +1,45 @@
+#include <iostream>
+#include <vector>
+using namespace std;
+
+// Paste your Solution class here (choose one implementation)
+class Solution {
+    int mod = 1000000007;
+public:
+    int perfectSum(vector<int>& arr, int k) {
+        int n = arr.size();
+        vector<int>prev(k+1, 0);
+        vector<int>curr(k+1, 0);
+        curr[0] = 1;
+        prev[0] = 1;
+        if(arr[0]<=k){
+            prev[arr[0]] = 1;
+        }
+        for(int i = 1; i<n; i++){                
+            for(int tar = 1; tar<=k; tar++){
+                int notTaken = prev[tar];
+                int take = 0;
+                if(arr[i]<=tar){
+                    take = prev[tar-arr[i]] % mod;
+                }
+                curr[tar] = (notTaken+take) % mod;
+            }
+            prev = curr;
+        }
+        return prev[k];
+    }
+};
+
+int main() {
+    int n, k;
+    cout << "Enter number of elements and target sum: ";
+    cin >> n >> k;
+    vector<int> arr(n);
+    cout << "Enter array elements: ";
+    for(int i=0; i<n; ++i) cin >> arr[i];
+
+    Solution sol;
+    int result = sol.perfectSum(arr, k);
+    cout << "Number of subsets with sum " << k << ": " << result << endl;
+    return 0;
+}