PathSum.java

package com.dbc;

public class PathSum {
    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;
        }
    }

    public boolean hasPathSum(TreeNode root, int targetSum) {
        if (root == null) return false;
        if (root.left == null && root.right == null && targetSum == root.val) return true;
        boolean leftRes = hasPathSum(root.left, targetSum - root.val);
        boolean rightRes = hasPathSum(root.right, targetSum - root.val);
        return leftRes || rightRes;
    }
}