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.
/**
* 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) //递归退出条件
return true;
int l = Depth(root.left);
int r = Depth(root.right);
if(Math.abs(l-r)>1) //把不符合条件的部分 剪枝
return false;
return isBalanced(root.left)&&isBalanced(root.right);
}
private int Depth(TreeNode root)
{
if(root == null)
return 0;
int Left = Depth(root.left);
int Right = Depth(root.right);
return (Left>Right)? (Left+1):(Right+1);
}
}
