100. Same Tree
Easy LeetCodeGiven the roots of two binary trees p and q, write a function to check if they are the same or not.
Two binary trees are considered the same if they are structurally identical, and the nodes have the same value.
Example 1
Input: p = [1,2,3], q = [1,2,3]
Output: true
Example 2
Input: p = [1,2], q = [1,null,2]
Output: false
Example 3
Input: p = [1,2,1], q = [1,1,2]
Output: false
Constraints
- The number of nodes in both trees is in the range [0, 100]
- -104 <= Node.val <= 104
How to solve the problem
Code
- Recursion
Python
# 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 p is None or q is None:
return p is q
# current node equal or not; left node equal or not; right node equal or not
return p.val == q.val and self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)
Complexity
- Time complexity: O(n), n == number of nodes
- Space complexity: O(n)
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