LeetCode:563. 二叉树的坡度
题目概述: 左右节点之间的差值的绝对值之和
dfs 递归
AC Code
/**
* 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) {
if(root == null) return ans;
dfs(root);
return ans;
}
public int dfs(TreeNode node){
if(node == null) return 0;
int a = dfs(node.left);
int b = dfs(node.right);
// 结果
ans += Math.abs(a - b);
// 返回左右子树的节点和
return a + b + node.val;
}
}