LeetCode 100. Same Tree.jpg

LeetCode 100. Same Tree

Description

Given two binary trees, 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:     1         1
          / \       / \
         2   3     2   3

        [1,2,3],   [1,2,3]

Output: true

Example 2:

Input:     1         1
          /           \
         2             2

        [1,2],     [1,null,2]

Output: false

Example 3:

Input:     1         1
          / \       / \
         2   1     1   2

        [1,2,1],   [1,1,2]

Output: false

描述

• 此題目是給定兩棵樹，判斷兩個(gè)樹是否相等.
• 兩顆樹相等意味著結(jié)構(gòu)，值要完全一樣.
• 此題目使用遞歸求解.

# -*- coding: utf-8 -*-
# @Author:             何睿
# @Create Date:        2018-12-28 19:06:08
# @Last Modified by:   何睿
# @Last Modified time: 2018-12-28 19:12:16

class TreeNode:
    def __init__(self, x):
        self.val = x
        self.left = None
        self.right = None

class Solution:
    def isSameTree(self, p, q):
        """
        :type p: TreeNode
        :type q: TreeNode
        :rtype: bool
        """
        # 如果第一個(gè)樹和第二個(gè)樹都是空，說明兩個(gè)樹是相等的，返回True.
        if not p and not q:
            return True
        # 如果有一個(gè)數(shù)為空另一個(gè)樹不為空，說明兩個(gè)樹一定不會相等
        if not p or not q:
            return False
        # 如果兩個(gè)樹的節(jié)點(diǎn)值不相等，則兩條樹不會相等，返回False
        if p.val != q.val:
            return False
        # 如果以上條件都通過了，說明兩個(gè)樹的當(dāng)前節(jié)點(diǎn)相等
        # 我們分別判斷這兩條樹的左子樹是否相等，右子樹是否相等
        left = self.isSameTree(p.left,q.left)
        right = self.isSameTree(p.right,q.right)
        # 返回最終結(jié)果
        return left and right

源代碼文件在這里.
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