K - Heavy Cargo dijkstar

来源poj2263

Big Johnsson Trucks Inc. is a company specialized in manufacturing big trucks. Their latest model, the Godzilla V12, is so big that the amount of cargo you can transport with it is never limited by the truck itself. It is only limited by the weight restrictions that apply for the roads along the path you want to drive.

Given start and destination city, your job is to determine the maximum load of the Godzilla V12 so that there still exists a path between the two specified cities.

Input

The input will contain one or more test cases. The first line of each test case will contain two integers: the number of cities n (2<=n<=200) and the number of road segments r (1<=r<=19900) making up the street network.

Then r lines will follow, each one describing one road segment by naming the two cities connected by the segment and giving the weight limit for trucks that use this segment. Names are not longer than 30 characters and do not contain white-space characters. Weight limits are integers in the range 0 - 10000. Roads can always be travelled in both directions.

The last line of the test case contains two city names: start and destination.

Input will be terminated by two values of 0 for n and r.

Output

For each test case, print three lines:

a line saying "Scenario #x" where x is the number of the test case

a line saying "y tons" where y is the maximum possible load

a blank line

Sample Input

4 3

Karlsruhe Stuttgart 100

Stuttgart Ulm 80

Ulm Muenchen 120

Karlsruhe Muenchen

5 5

Karlsruhe Stuttgart 100

Stuttgart Ulm 80

Ulm Muenchen 120

Karlsruhe Hamburg 220

Hamburg Muenchen 170

Muenchen Karlsruhe

0 0

Sample Output

Scenario #1

80 tons

Scenario #2

170 tons

找到n的最大的载重，似乎之前做过，只要用dijkstar变形一下，每次找最大的来搜，收到end就是最大的了

#include<iostream>

#include<stdio.h>

#include<stdlib.h>

#include <iomanip>

#include<cmath>

#include<float.h>

#include<string.h>

#include<algorithm>

#define sf scanf

#define pf printf

#define scf(x) scanf("%d",&x)

#define scff(x,y) scanf("%d%d",&x,&y)

#define prf(x) printf("%d\n",x)

#define mm(x,b) memset((x),(b),sizeof(x))

#include<vector>

#include<queue>

//#include<map>

#define rep(i,a,n) for (int i=a;i<n;i++)

#define per(i,a,n) for (int i=a;i>=n;i--)

typedef long long ll;

const ll mod=1e9+7;

const double eps=1e-8;

const int inf=0x3f3f3f3f;

using namespace std;

const double pi=acos(-1.0);

const int N=1e5+10;

char name[205][35];

int map[205][205];

int visit[205];

int value[205];

int find(int n,char b[35])

{

	rep(i,0,n)

	{

		if(strcmp(b,name[i])==0)

		return i;

	}

	return -1;

}

int dijkstra(int n,int star,int end)

{

	int pos,MAX=0;

	value[star]=inf;

	rep(i,0,n)

	{

		if(map[star][i]!=-1)

		value[i]=map[star][i];

		if(MAX<value[i]&&i!=star)

		{

			MAX=value[i];

			pos=i;

		}

	}

	visit[star]=1;

	visit[pos]=1;

	if(pos==end) return MAX;

	rep(i,1,n)

	{

		MAX=0;

		rep(j,0,n)

		{

			if(map[pos][j]!=-1&&visit[j]==0)

			{

				if(value[j]==-1) value[j]=min(map[pos][j],value[pos]);

				else value[j]=max(value[j],min(map[pos][j],value[pos]));

			}

		}

		rep(j,0,n)

		{

			if(MAX<value[j]&&j!=star&&visit[j]==0)

			{

				pos=j;

				MAX=value[j];

			}

		}

		visit[pos]=1;

		if(pos==end) return value[end];

	}

	return value[end];

}

int main()

{

	int n,m,k;

	int bits=1;

	char a[35],b[35];

	while(~scff(n,m)&&n)

	{

		mm(visit,0);

		mm(value,-1);

		mm(map,-1);

		int cas=0;

		while(m--)

		{

			sf("%s%s%d",a,b,&k);

			int x,y;

			x=find(cas,a);

			if(x==-1)

			{

				x=cas;

				strcpy(name[cas++],a);

			}

			y=find(cas,b);

			if(y==-1)

			{

				y=cas;

				strcpy(name[cas++],b);

			}

			map[x][y]=map[y][x]=k;

		}

		sf("%s%s",a,b);

		int star,end;

		star=find(cas,a);end=find(cas,b);

		int ans=dijkstra(n,star,end);

		pf("Scenario #%d\n%d tons\n\n",bits++,ans);

	}

	return 0;

}

巴特西