[Leetcode] balanced binary tree

Balanced Binary Tree

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 SubtreesEveryNode never differ by more than 1.

Algorithm ideas:

Determine whether each subtree is a balanced binary tree. To prevent redundant computing, it is best to adopt post-order traversal.

The Code is as follows:

 1 public class Solution { 2    public boolean isBalanced(TreeNode root) { 3         if(root == null || (root.left == null && root.right == null)) 4             return true; 5         if(!isBalanced(root.left) || !isBalanced(root.right)) 6             return false; 7         int left = getHeight(root.left); 8         int right = getHeight(root.right); 9         if(Math.abs(right - left) > 1) return false;10         return true;11     }12     13     private int getHeight(TreeNode root){14         if(root == null) return 0;15         if(root.left == null && root.right == null) return 1;16         int left = 0,right = 0;17         if(root.left != null) left = getHeight(root.left);18         if(root.right != null) right = getHeight(root.right);19         return Math.max(left, right) + 1;20     }21 }