Given a binary tree, determine if it is height-balanced.
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
Solution
class TreeNode:
def __init__(self, val=0, left=None, right=None):
self.val = val
self.left = left
self.right = right
class Solution:
def height(self, root):
if root is None:
return 0
return max(self.height(root.left), self.height(root.right)) + 1
def isBalanced(self, root: Optional[TreeNode]) -> bool:
if root is None:
return True
left_height = self.height(root.left)
right_height = self.height(root.right)
if abs(left_height - right_height) <= 1 and self.isBalanced(root.left) and self.isBalanced(root.right):
return True
return False