Same Tree - Solution
Solutions and explanations

Video Explanation

# 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 isSameTree(self, p: Optional[TreeNode], q: Optional[TreeNode]) -> bool:
        if not p and not q:
            return True
        if not(p and q): #not p or not q
            return False
        return p.val == q.val and self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)

Complexity Analysis

  • Time Complexity: O(n) where n is the number of nodes in the tree.
  • Space Complexity: O(h) where h is the height of the tree, due to the recursion stack.

Note: In the worst case, where the tree is skewed, h can be as large as n. In the best case, such as a balanced binary tree, h is O(log n).