Add 494_Target_Sum.java

Author: Sean Prashad

Dynamic Programming/494_Target_Sum.java

@@ -0,0 +1,23 @@
+class Solution {
+    public int findTargetSumWays(int[] nums, int S) {
+        if (nums == null || nums.length == 0) {
+            return 0;
+        }
+
+        return dfs(nums, S, 0, 0);
+    }
+
+    private int dfs(int[] nums, int S, int sum, int idx) {
+        if (idx == nums.length) {
+            if (sum == S) {
+                return 1;
+            }
+            return 0;
+        }
+
+        int add = dfs(nums, S, sum + nums[idx], idx + 1);
+        int minus = dfs(nums, S, sum - nums[idx], idx + 1);
+
+        return add + minus;
+    }
+}