110. Balanced Binary Tree

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

Python

• 雙層的recursion...

class Solution:
    def get_depth(self, node):
        if not node:
            return -1
        return 1 + max(self.get_depth(node.left), self.get_depth(node.right))

    def check(self, node):
        if not node:
            return True
        return abs(self.get_depth(node.left) - self.get_depth(node.right)) <= 1 \
            and self.check(node.left) \
            and self.check(node.right)

    def isBalanced(self, root: Optional[TreeNode]) -> bool:
        return self.check(root)