题目描述:
给定两个二叉树,编写一个函数来检验它们是否相同。
如果两个树在结构上相同,并且节点具有相同的值,则认为它们是相同的。
knowledge point:树的中序遍历(递归),层次遍历(队列)
解法一:递归实现中序遍历
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def isSameTree(self, p, q):
if not p and not q:
return True
elif p is not None and q is not None:
if p.val == q.val:
return self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)
else:
return False
else:
return False
解法二:非递归实现树的层次遍历
from collections import deque
class Solution:
def isSameTree(self, p, q):
def check(p, q):
if not p and not q:
return True
if not q or not p:
return False
if p.val != q.val:
return False
return True
deq = deque([(p, q),])
while deq:
p, q = deq.popleft()
if not check(p, q):
return False
if p:
deq.append((p.left, q.left))
deq.append((p.right, q.right))
return True