100. Same Tree

Description:

Given the root of a binary tree, return its maximum depth.

A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

# 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
'''
[1] top-down)

idea::
check whether cur values are same first.
check whether left-subtree and right-subtree are same or not.

code::
    def isSameTree(self, p: Optional[TreeNode], q: Optional[TreeNode]) -> bool:
        if not p and not q:
            return True
        elif (p and not q) or (not p and q):
            return False

        return (p.val==q.val) and self.isSameTree(p.left,q.left) and self.isSameTree(p.right,q.right)

-T/C: O(n) # n==the number of nodes
-S/C: O(h) # h==height of trees
'''

class Solution:
    def isSameTree(self, p: Optional[TreeNode], q: Optional[TreeNode]) -> bool:
        if not p and not q:
            return True
        elif (p and not q) or (not p and q):
            return False

        return (p.val==q.val) and self.isSameTree(p.left,q.left) and self.isSameTree(p.right,q.right)