563. 二叉树的坡度

• 前言
• 题目
• 源码

前言

后续遍历，递归。盗图一张过程

题目

官方题目

源码

/**
 * Definition for a binary tree node.
 * 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;
 *     }
 * }
 */
class Solution {
    int ans=0;
    public int findTilt(TreeNode root) {
        helper(root);
        return ans;

    }
    public int helper(TreeNode node){
        if(node==null){
            return 0;
        }
        int left=helper(node.left);
        int right=helper(node.right);
        ans+=Math.abs(left-right);
        return left+right+node.val;
    }
}