chore(Java): add target-sum-subsets problem (#687)

algorithms/Java/backtracking/target-sum-subsets.java

@@ -0,0 +1,49 @@
+// Target sum subsets is a program to print all subsets of an array (given by user) such that sum of all elements in subset equal to a target sum given by user
+
+// Algorithm Type: Backtracking
+// Time Complexity: O(2^N)
+
+import java.io.*;
+import java.util.*;
+
+public class targetSumSubsets {
+
+    public static void main(String[] args) throws Exception {
+        Scanner scn = new Scanner(System.in);
+
+        // input size of array
+        int n = scn.nextInt();
+
+        // input elements of array
+        int[] arr = new int[n];
+        for(int i=0; i<n; i++){
+            arr[i] = scn.nextInt();
+        }
+
+        // input target sum
+        int tar = scn.nextInt();
+
+        // calling our function - printTargetSumSubsets
+        printTargetSumSubsets(arr, 0, "", 0, tar);
+        scn.close();
+    }
+
+    // set is the subset, sum is the sum so far for that subset
+    public static void printTargetSumSubsets(int[] arr, int idx, String set, int sum, int tar){   
+        if (idx == arr.length){
+            if (sum == tar){
+                System.out.println(set + " ");
+            }
+            return;
+        }
+
+        // pick
+        printTargetSumSubsets(arr, idx + 1, set + arr[idx] + " ", sum + arr[idx], tar);
+       
+        //not pick
+        printTargetSumSubsets(arr, idx + 1, set, sum, tar);    
+    }
+
+    
+
+}