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leetcode_balanced binary tree

admin 11月 13, 2020 0

Balanced Binary Tree

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.
（判断是否是平衡二叉树）

Example:

1. 递归


# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

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