zoukankan      html  css  js  c++  java
  • 【leetcode】1257. Smallest Common Region

    题目如下:

    You are given some lists of regions where the first region of each list includes all other regions in that list.

    Naturally, if a region X contains another region Y then X is bigger than Y.

    Given two regions region1region2, find out the smallest region that contains both of them.

    If you are given regions r1r2 and r3 such that r1 includes r3, it is guaranteed there is no r2 such that r2 includes r3.


    It's guaranteed the smallest region exists.

    Example 1:

    Input:
    regions = [["Earth","North America","South America"],
    ["North America","United States","Canada"],
    ["United States","New York","Boston"],
    ["Canada","Ontario","Quebec"],
    ["South America","Brazil"]],
    region1 = "Quebec",
    region2 = "New York"
    Output: "North America"

    Constraints:

    • 2 <= regions.length <= 10^4
    • region1 != region2
    • All strings consist of English letters and spaces with at most 20 letters.

    解题思路:首先递归找出region1所属的regions链,并保持结果;然后再递归查找region2所属的regions链,找到第一个region在region1所属的regions链即可。

    代码如下:

    class Solution(object):
        def findSmallestRegion(self, regions, region1, region2):
            """
            :type regions: List[List[str]]
            :type region1: str
            :type region2: str
            :rtype: str
            """
            dic = {}
            for region in regions:
                parent = region[0]
                for i in range(1,len(region)):
                    dic[region[i]] = parent
    
            dic_region1 = {}
            while region1 in dic:
                dic_region1[region1] = 1
                region1 = dic[region1]
    
            while region2 in dic:
                if region2 in dic_region1:
                    return region2
                region2 = dic[region2]
            return regions[0][0]
  • 相关阅读:
    作业2 求题目中的数
    2013 C#单元测试
    实现项目WC
    带括号多项式版四则运算
    20道简单加减法随机生成程序扩展版体会
    20道简单加减法随机生成程序
    Jeesite 集成微信支付接口
    第一节:JAVA 语言的学习目标
    vector(未完)
    关于phpstorm端口63342的修改经历
  • 原文地址:https://www.cnblogs.com/seyjs/p/11878841.html
Copyright © 2011-2022 走看看