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 left and right subtrees of every node differ in height by no more than 1.
Example 1:
Input: root = [3,9,20,null,null,15,7]
Output: true
Example 2:
Input: root = [1,2,2,3,3,null,null,4,4]
Output: false
Example 3:
Input: root = []
Output: true
Constraints:
- The number of nodes in the tree is in the range [0, 5000].
- -104 <= Node.val <= 104
/**
* 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 root) {
if(root==null){
return true;
}
int left = depth(root.left);
int right = depth(root.right);
if(left-right>1 || right-left>1){
return false;
}
return isBalanced(root.left)&&isBalanced(root.right);
}
public int depth(TreeNode root) {
if(root == null){
return 0;
}
if(root.left==null&&root.right==null){
return 1;
}
int left = depth(root.left);
int right = depth(root.right);
return left>right?left+1:right+1;
}
}