BinarySearch 0293 Symmetric Binary Tree

Problem statement

https://binarysearch.com/problems/Symmetric-Binary-Tree/

Solution

Equal to Leetcode 0101 Symmetric Tree.

Complexity

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

Code

class Solution:
    def solve(self, root):
        def dfs(n1, n2):
            if not n1 and not n2: return True
            if not n1  or not n2: return False
            
            return n1.val == n2.val and dfs(n1.left, n2.right) and dfs(n1.right, n2.left)
        
        if not root: return True
        return dfs(root.left, root.right)