Leetcode 0965. Univalued Binary Tree

Problem statement

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

Solution

Just use simple dfs.

Complexity

It is O(n) for time and O(h) for space.

Code

class Solution:
    def isUnivalTree(self, root):
        if not root: return True
        if root.left and root.left.val != root.val: return False
        if root.right and root.right.val != root.val: return False
        return self.isUnivalTree(root.left) and self.isUnivalTree(root.right)