Add recursive solution for Subset Sum Problem

knapsack/subset_sum_using_recursion

@@ -0,0 +1,22 @@
+def is_subset_sum_recursive(arr, n, target):
+    # Base cases
+    if target == 0:
+        return True  # A subset with sum 0 always exists (empty subset)
+    if n == 0:
+        return False  # No elements left to form the sum
+
+    # If the current element is greater than the target, ignore it
+    if arr[n-1] > target:
+        return is_subset_sum_recursive(arr, n-1, target)
+
+    # Otherwise, check if sum can be obtained by including or excluding the current element
+    return (is_subset_sum_recursive(arr, n-1, target) or
+            is_subset_sum_recursive(arr, n-1, target - arr[n-1]))
+
+arr = [3, 34, 4, 12, 5, 2]
+target = 9
+result = is_subset_sum_recursive(arr, len(arr), target)
+print(f"Subset with sum {target} {'exists' if result else 'does not exist'}")
+
+Time Complexity: O(2^N)
+Space Complexity: O()