POJ. 2253 Frogger (Dijkstra ) 题意分析 首先给出n个点的坐标,其中第一个点的坐标为青蛙1的坐标,第二个点的坐标为青蛙2的坐标.给出的n个点,两两双向互通,求出由1到2可行通路的所有步骤当中,步长最大值. 在dij原算法的基础上稍作改动即可.dij求解的是单源最短路,现在求解的是步长最大值,那么更新原则就是,当前的这一步比保存的步如果要大的话,就更新,否则就不更新. 如此求解出来的就是单源最大步骤. 代码总览 #include <cstdio> #include &…

POJ 2253 Frogger Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on another stone. He plans to visit her, but since the water is dirty and full of tourists' sunscreen, he wants to avoid swimmin…

题目链接:http://poj.org/problem?id=2253 Frogger Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 25773   Accepted: 8374 Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on an…

题目链接: http://poj.org/problem?id=2253 Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on another stone. He plans to visit her, but since the water is dirty and full of tourists' suns…

http://poj.org/problem?id=2253 题意: 有两只青蛙A和B,现在青蛙A要跳到青蛙B的石头上,中间有许多石头可以让青蛙A弹跳.给出所有石头的坐标点,求出在所有通路中青蛙需要跳跃距离的最小值. 思路: dijkstra算法的变形.本来是dist是记录最短距离,在这道题中可以把它变为已经跳过的最大距离,稍微改一下松弛算法就可以.具体见代码. #include<iostream> #include<algorithm> #include<string>…

传送门 Frogger Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 39453   Accepted: 12691 Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on another stone. He plans to visit…

题意: 题目撰写者的英语真是艰难晦涩,看了别人题解,才知道这题题意. 两个forger 一个froger 要蹦到另外一个froger处,他们的最短距离是这样定义的 : The frog distance (humans also call it minimax distance) between two stones therefore is defined as the minimum necessary jump range over all possible paths between t…

Til the Cows Come Home 题目链接: http://acm.hust.edu.cn/vjudge/contest/66569#problem/A Description The input will contain one or more test cases. The first line of each test case will contain the number of stones n (2<=n<=200). The next n lines each con…

题意:求点1到点2的路径中,权值最大的那条边,其最小值是多少. 分析:最大值最小化.可以将迪杰斯特拉模板中的松弛操作加以修改,在O(n^2)的时间内解决该问题.其中需要注意的是,dist[i]指的是:走到点i的路径上,权值最大的边权.当每次找到最小的dist[u]之后,松弛操作是:对于点v,若max(d[u],G[u][v])>d[v],那么将d[v]跟新为max(d[u],G[u][v]).也就是说通过u的路径上最大的边权值如果小于的dist[v],显然dist[v]可以变得更小. #incl…

题意:要从起点的石头跳到终点的石头,设The frog distance为从起点到终点的某一路径中两点间距离的最大值,问在从起点到终点的所有路径中The frog distance的最小值为多少. 分析: 解法一:Dijkstra,修改最短路模板,d[u]表示从起点到u的所有路径中两点间距离的最大值的最小值. #include<cstdio> #include<cstring> #include<cstdlib> #include<cctype> #incl…

http://poj.org/problem?id=2253 题意 : 题目是说,有这样一只青蛙Freddy,他在一块石头上,他呢注意到青蛙Fiona在另一块石头上,想去拜访,但是两块石头太远了,所以他只有通过别的石头跳过去,所以,从他的石头到Fiona的石头每一条可走的路,假设是n条,就需要你求出frog distance,这个所谓的距离就是指这n条路中,每条路选取组成这条路中最长的那边,最后一共有n条边,找这n条边里最短的那一条输出. 思路 : 就是一个最短路的问题,不过不需要求最短路的权值…

Frogger Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 24879   Accepted: 8076 Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on another stone. He plans to visit her,…

题目链接:http://poj.org/problem?id=1797 题意:给出两只青蛙的坐标A.B,和其他的n-2个坐标,任一两个坐标点间都是双向连通的.显然从A到B存在至少一条的通路,每一条通路的元素都是这条通路中前后两个点的距离,这些距离中又有一个最大距离.现在要求求出所有通路的最大距离,并把这些最大距离作比较,把最小的一个最大距离作为青蛙的最小跳远距离. 有一个明显的方法就是dfs一遍但是肯定会te,所以可以考虑一下用dp的思想. 类似记忆化搜索的思想,由于数据比较小所以不用记忆化搜索…

题目 这里的dijsktra的变种代码是我看着自己打的,终于把代码和做法思路联系上了,也就是理解了算法——看来手跟着画一遍真的有助于理解. #define _CRT_SECURE_NO_WARNINGS #include<string.h> #include<stdio.h> #include<math.h> #include<algorithm> using namespace std; ; #define typec double const typec…

青蛙跳跃,题意大概是:青蛙从起点到终点进行一次或多次的跳跃,多次跳跃中肯定有最大的跳跃距离.求在所有的跳跃中,最小的最大跳跃距离SF-_-(不理解?看题目吧). 可以用最小生成树完成.以起点为根,生成一棵最小生成树,直到树里包含了终点. 或者这么说吧,类似于Kruskal算法,我们每次选取不成环的最小边,直到这棵树选取了通往终点的最小边,那么最后选择的这条边必然是在树中最大的一条边,而且在其余的边中是最小的.你不会找到比这条边小的最大距离,因为比它小的最小距离都在树里了,而未选取该边前树中不包含…

Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on another stone. He plans to visit her, but since the water is dirty and full of tourists' sunscreen, he wants to avoid swimming and…

Frogger Time Limit: 1000MS   Memory Limit: 65536K Total Submissions:57696   Accepted: 18104 Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on another stone. He plans to visit her,…

题意:湖中有很多石头,两只青蛙分别位于两块石头上.其中一只青蛙要经过一系列的跳跃,先跳到其他石头上,最后跳到另一只青蛙那里.目的是求出所有路径中最大变长的最小值(就是在到达目的地的路径中,找出青蛙需要跳跃的最大边长的最小的值). 思路:warshall算法 hint:似懂非懂 课本代码: #include<iostream> #include<cmath> #include<stdio.h> #include<cstring> bool con[210][2…

Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on another stone. He plans to visit her, but since the water is dirty and full of tourists' sunscreen, he wants to avoid swimming and…

题意:有两只青蛙,a在第一个石头,b在第二个石头,a要到b那里去,每种a到b的路径中都有最大边,求所有这些最大边的最小值.思路:将所有边长存起来,排好序后,二分枚举答案. 时间复杂度比较高,344ms. #include <iostream> #include <stdio.h> #include <string.h> #include <algorithm> #include <math.h> using namespace std; ; co…

题意:想给你公青蛙位置,再给你母青蛙位置,然后给你剩余位置,问你怎么走,公青蛙全力跳的的最远距离最小. 思路:这里不是求最短路径,而是要你找一条路,青蛙走这条路时,对他跳远要求最低.这个思想还是挺好迁移的,原来我们用mp[i][j]表示i到j最短路径,那么我们现在用它表示i到j最大步伐,然后每次比较,只要最大步伐比他小,那么我们就走新的路.注意最后是mp[1][2],一直mp[1][n]没改无限WA. 代码; #include<cstdio> #include<set> #incl…

POJ 2253 Frogger题目意思就是求所有路径中最大路径中的最小值. #include<iostream> #include<cstdio> #include<string.h> #include <utility>//make_pair的头文件 #include<math.h> using namespace std; ; double map[maxn][maxn]; int n; typedef struct pair<int…

题目传送门 /* 最短路:Floyd算法模板题 */ #include <cstdio> #include <iostream> #include <algorithm> #include <cmath> #include <cstring> #include <string> #include <vector> using namespace std; + ; const int INF = 0x3f3f3f3f; do…

Frogger Time Limit:1000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u Submit Status Practice POJ 2253 Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on another stone…

传送门: http://poj.org/problem?id=2253 Frogger Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 58328   Accepted: 18293 Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on a…

题目链接:http://poj.org/problem?id=2253 Frogger Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 38366   Accepted: 12357 Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on a…

链接:poj 2253 题意:给出青蛙A,B和若干石头的坐标,现青蛙A想到青蛙B那,A可通过随意石头到达B, 问从A到B多条路径中的最长边中的最短距离 分析:这题是最短路的变形,曾经求的是路径总长的最小值,而此题是通路中最长边的最小值,每条边的权值能够通过坐标算出,由于是单源起点,直接用SPFA算法或dijkstra算法就能够了 SPFA 16MS #include<cstdio> #include<queue> #include<cmath> #include<…

原题链接:http://poj.org/problem?id=2253 Frogger Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 30637   Accepted: 9883 Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on an…

点击打开链接 Frogger Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 21653   Accepted: 7042 Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on another stone. He plans to visi…

Time Limit: 1000MS Memory Limit: 65536K Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on another stone. He plans to visit her, but since the water is dirty and full of tourists' s…