【LeetCode】110.Balanced Binary Tree

题目：

Given a binary tree, determine if it is height-balanced.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

解答：

用递归方式处理。需要一个计算子树深度的递归。

代码：

/**
* Definition for binary tree
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
public class Solution {
// use recursion
public int getHeight(TreeNode root){
if(root == null)
return 0;
int leftHeight = getHeight(root.left);
int rightHeight = getHeight(root.right);
return Math.max(leftHeight, rightHeight) + 1;
}

public boolean isBalanced(TreeNode root) {
if(root == null)
return true;
if(isBalanced(root.left) && isBalanced(root.right)){
int left = getHeight(root.left);
int right = getHeight(root.right);
return Math.abs(left - right) <= 1;
}
return false;
}
}