树中是否存在路径和为 sum leecode java

https://oj.leetcode.com/problems/path-sum/

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public boolean hasPathSum(TreeNode root, int sum) {
        if(root==null) return false;
        if(root.left==null&&root.right==null)
        {
            if(sum==root.val) return true;

        }

        return hasPathSum(root.left,sum-root.val)||hasPathSum(root.right,sum-root.val);

    }
}