LeetCode 110. Balanced Binary Tree

파이썬 알고리즘 인터뷰 문제 48번(리트코드 110번) Balanced Binary Tree
https://leetcode.com/problems/balanced-binary-tree/

나의 풀이

# 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: Optional[TreeNode]) -> bool:
        if not root:
            return True

        def depth(root):
            if not root:
                return 0
            return 1 + max(depth(root.left), depth(root.right))
            
        if abs(depth(root.left) - depth(root.right)) > 1:
            return False
        else:
            return self.isBalanced(root.left) and self.isBalanced(root.right)

다른 풀이

# 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: Optional[TreeNode]) -> bool:
        def depth(root):
            if not root:
                return 0
            left = depth(root.left)
            right = depth(root.right)
            if left == -1 or right == -1 or abs(left-right) > 1:
                return -1
            return max(left, right)+1
        return depth(root) != -1