zoj1857Fire Station最短路

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <climits>
#include <string>
#include <iostream>
#include <map>
#include <cstdlib>
#include <list>
#include <set>
#include <queue>
#include <stack>
#include<math.h>
using namespace std;
int dis[555];
int dist[555];
int Map[555][555];
const int INF=0xfffffff;
int m;
void floyd()
{
    for(int k=1;k<=m;k++)
    for(int i=1;i<=m;i++){
        for(int j=1;j<=m;j++){
            Map[i][j]=min(Map[i][j],Map[i][k]+Map[k][j]);
        }
    }
}

void spfa(int x)
{
    int vis[555];
    memset(vis,0,sizeof(vis));
    for(int i=1;i<=m;i++) dist[i]= dis[i];
    queue<int> q;
    q.push(x) ; dist[x]= 0 ;vis[x]=1;
    while(!q.empty()){
        int cur= q.front() ;q.pop();
        vis[cur]=0;
        for(int i=1;i<=m;i++){
            if(dist[i]>dist[cur]+Map[cur][i]){
                dist[i]=dist[cur]+Map[cur][i];
                if(!vis[i]){
                    vis[i]=1;q.push(i);
                }
            }
        }
    }
}
int main()
{
    int n;int a,b,c;
    int val[555],vis[555];
    char str[100];
    while(scanf("%d%d",&n,&m)!=EOF){
        memset(vis,0,sizeof(vis));
        memset(val,0,sizeof(val));
        for(int i=1;i<=m;i++)
        for(int j=1;j<=m;j++)
        if(i==j) Map[i][j]=0;else Map[i][j]=INF;
        for(int i=1;i<=m;i++)
            dis[i]=INF;
        for(int i=0;i<n;i++){
            scanf("%d",&val[i]);vis[val[i]]= 1; dis[val[i]]= 0;
        }
        getchar();
        while(gets(str)&&strlen(str)){
            sscanf(str,"%d%d%d",&a,&b,&c);
            Map[a][b]=Map[b][a]=c;
        }
        floyd();
        for(int i=0;i<n;i++){
            for(int j=1;j<=m;j++){
                if(vis[j]) continue;
                if(dis[j]>Map[val[i]][j]) dis[j] = Map[val[i]][j];
            }
        }
        for(int i=0;i<n;i++){
            dis[val[i]]=0;
        }
        int Max=0;
        for(int i=1;i<=m;i++)
            if(dis[i]>Max) Max= dis[i];
        int flag=1;
        for(int i=m;i>=1;i--){
            if(vis[i]) continue;
            int Max1=0;
            spfa(i);
            for(int j=1;j<=m;j++){
                if(vis[j]) continue;
                if(dist[j]>Max1) Max1=dist[j];
            }
            if(Max1<=Max){
                Max= Max1; flag= i;
            }

        }
        printf("%d\n",flag);
    }
    return 0;
}