leetcode@Tree_563_Binary_Tree_Tilt

Given a binary tree, return the tilt of the whole tree.

The tilt of a tree node is defined as the absolute difference between the sum of all left subtree node values and the sum of all right subtree node values. Null node has tilt 0.

The tilt of the whole tree is defined as the sum of all nodes' tilt.

Example:

Input:          1       /   \      2     3Output: 1Explanation: Tilt of node 2 : 0Tilt of node 3 : 0Tilt of node 1 : |2-3| = 1Tilt of binary tree : 0 + 0 + 1 = 1

java :

/** * Definition for a binary tree node. * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    int res = 0;public int findTilt(TreeNode root){postOrder(root);return res;}public int postOrder(TreeNode root){if (root == null)return 0; int leftSum = postOrder(root.left);     int rightSum = postOrder(root.right);res += Math.abs(rightSum - leftSum);return leftSum+rightSum+root.val;}}