[리트코드 leetcode] 110. Balanced Binary Tree

leetcode.com/problems/balanced-binary-tree/

Balanced Binary Tree - LeetCode

 

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def isBalanced(self, root: TreeNode) -> bool:
        if not root:
            return True
        
        def dfs(node):
            if not node:
                return 0
            
            left = dfs(node.left)
            right = dfs(node.right)
            
            if left == -1 or right == -1:
                return -1
            if left - right > 1 or left-right <-1:
                return -1
      
            return max(left,right)+1
        
        return dfs(root)!=-1