/*
* public class TreeNode {
* int val = 0;
* TreeNode left = null;
* TreeNode right = null;
* }
*/
public class Solution {
/**
*
* @param root TreeNode类
* @param sum int整型
* @return bool布尔型
*/
public boolean hasPathSum (TreeNode root, int sum) {
if(root==null) return false;
sum -= root.val;
if(root.left==null && root.right == null){ // 叶子节点
return sum==0;
} else { // 非叶子节点
return (root.left!=null && hasPathSum(root.left, sum)) || (root.right!=null && hasPathSum(root.right, sum));
}
}
}