112. Path Sum

java/112-Path-Sum.java

@@ -0,0 +1,33 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+class Solution {
+    private boolean isLeafNode(TreeNode node) {
+        return ((node.left == null) && (node.right == null));
+    }
+
+    public boolean hasPathSum(TreeNode root, int targetSum) {
+        // Edge case: No nodes
+        if(root == null) {
+            return false;
+        }
+
+        targetSum -= root.val;
+        if(isLeafNode(root)) {
+            return (targetSum == 0);
+        }
+        return hasPathSum(root.left, targetSum) || hasPathSum(root.right, targetSum);
+    }
+}