path sum

input.txt

@@ -1 +1,2 @@
-1,2,2,3,3,null,null,4,4
+5,4,8,11,null,13,4,7,2,null,null,null,1
+22

src/com/dsa/trees/DepthFirstTraversal.java

@@ -4,12 +4,14 @@ import java.io.BufferedReader;
 import java.io.FileReader;
 import java.io.IOException;
 import java.util.LinkedList;
+import java.util.Optional;
 import java.util.Queue;
 
 public class DepthFirstTraversal {
     public static void main(String[] args) {
         try (BufferedReader reader = new BufferedReader(new FileReader("input.txt"))) {
             String[] elements = reader.readLine().trim().split(",");
+            int targetSum = Optional.ofNullable(reader.readLine()).map(Integer::parseInt).orElse(0);
             Queue<TreeNode> queue = new LinkedList<>();
             TreeNode root = new TreeNode(Integer.parseInt(elements[0]));
             queue.offer(root);
@@ -29,6 +31,7 @@ public class DepthFirstTraversal {
             }
             System.out.println("MinDepth: " + minDepth(root));
             System.out.println("isBalanced: " + isBalanced(root));
+            System.out.println("PathSum Target: " + targetSum + " isPresent: " + hasPathSum(root, targetSum));
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
@@ -72,4 +75,13 @@ public class DepthFirstTraversal {
         if (weight > 1) return -1;
         return Math.max(leftHeight, rightHeight) + 1;
     }
+
+    public static boolean hasPathSum(TreeNode root, int targetSum) {
+        if(root == null) return false;
+        if (root.left == null && root.right == null && root.val == targetSum) return true;
+        int requiredNewSum = targetSum - root.val;
+        boolean hasPathSumLeft = hasPathSum(root.left, requiredNewSum);
+        if (hasPathSumLeft) return true;
+        return hasPathSum(root.right, requiredNewSum);
+    }
 }