LeetCode 112. 路径总和 Java

1.层序遍历，一个队列存放节点，一个队列存放到当前节点的值。

2.递归

/**
 * 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 sum == root.val;
        }
        return hasPathSum(root.left,sum-root.val) || hasPathSum(root.right,sum-root.val);
    }
}