112 路径总和
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public boolean hasPathSum(TreeNode root, int sum) {
if (root == null)
return false;
if (root.left == null && root.right == null )
return (root.val == sum);
return hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val);
}
}