Description：
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.
判断是不是二叉平衡树，递归还是递归。
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public boolean isBalanced(TreeNode root) {
if(root == null)
return true;
int l = getDepth(root.left, 1);
int r = getDepth(root.right, 1);
if(Math.abs(l-r) > 1) {
return false;
}
else {
return isBalanced(root.left) && isBalanced(root.right);
}
}
public int getDepth(TreeNode root, int depth) {
if(root == null) {
return depth;
}
else {
return Math.max(getDepth(root.left, depth+1), getDepth(root.right, depth+1));
}
}
}
LeetCode——Balanced Binary Tree
原文：http://www.cnblogs.com/wxisme/p/4588259.html