Symmetric Tree - LeetCode 101 (Easy)

symmetric_tree_leetcode.py

# 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 isSymmetric(self, root: Optional[TreeNode]) -> bool:
        # Base case for root if it is None then we just simply return true
        if not root:
            return True
        
        # Recurstion function which will implement cases to check if tree has reached the end or if tree is not mirror
        def isMirror(tree1, tree2):
            # Case to check if we reached the end of all nodes
            if not tree1 or not tree2:
                return tree1 == tree2
            # Case to check if the values are not matched i.e., this is not a mirror tree 
            if tree1.val != tree2.val:
                return False
            # recursion call to check (left , right) and (rigt, left) of the specific tree
            return isMirror(tree1.left, tree2.right) and isMirror(tree1.right, tree2.left)
            
        #  first call to the recursion function with left and right nodes of root
        return isMirror(root.left, root.right)