Heavy Cargo
| Time Limit: 1000MS | Memory Limit: 65536K | |
| Total Submissions: 3768 | Accepted: 2013 |
Description
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
Source
题意：求各城市每条给定起点和终点间通路的最小负载，并据此求出所有最小负载中的最大值.
思路：题目给的是城市名用map.
收获：map用法 + Floyd
#include <cstdio>
#include <iostream>
#include <cstdlib>
#include <algorithm>
#include <ctime>
#include <cmath>
#include <string>
#include <cstring>
#include <stack>
#include <queue>
#include <list>
#include <vector>
#include <map>
#include <set>
using namespace std;
const int INF=0x3f3f3f3f;
const double eps=1e-10;
const double PI=acos(-1.0);
#define maxn 500
map<string, int> a;
char s1[32];
char s2[32];
int c[maxn][maxn];
int v[maxn][maxn];
int pre[maxn][maxn];
int main()
{
int n, m, w;
int cas = 0;
while(~scanf("%d%d",&n,&m)&&(n+m))
{
int cnt = 0;
memset(c, 0, sizeof c);
for(int i = 0; i < m; i++)
{
scanf("%s%s%d", s1, s2, &w);
if(!a.count(s1))
a[s1] = cnt++;
if(!a.count(s2))
a[s2] = cnt++;
c[a[s1]][a[s2]] = c[a[s2]][a[s1]] = w;
}
// map<string, int>::iterator it;
// for(it=a.begin();it!=a.end();++it)
// cout<<"key: "<<it->first <<" value: "<<it->second<<endl;
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++)
{
v[i][j] = c[i][j];
pre[i][j] = i;
}
for(int k = 0; k < n; k++)
for(int i = 0; i<n; i++)
for(int j = 0; j < n; j++)
{
v[i][j] = max(v[i][j], min(v[i][k],v[k][j]));
pre[i][j] = pre[k][j];
}
scanf("%s%s",s1,s2);
printf("Scenario #%d\n", ++cas);
printf("%d tons\n",v[a[s1]][a[s2]]);
puts("");
}
return 0;
}