Balanced Binary Tree

Posted 2020-10-03 Quest

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; }
 * }
 */
class Solution {
    public boolean isBalanced(TreeNode node) {
        if(node == null){
            return true;
        }

        int leftDeepth = calDeepth(node.left);
        int rightDeepth = calDeepth(node.right);

        if(Math.abs(leftDeepth-rightDeepth)>1){
            return false;
        }

        return isBalanced(node.left)&&isBalanced(node.right);
    }
    
    // 获取二叉树的深度
    private int calDeepth(TreeNode node){
        if(node==null){
            return 0;
        }
        int leftDeepth = calDeepth(node.left);
        int rightDeepth = calDeepth(node.right);

        return 1+(leftDeepth > rightDeepth ? leftDeepth : rightDeepth);
    }
    
}