2017 9 11 noip模拟赛T2

Posted 2020-10-06 1 2 f s_____

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int N=205;
int map[N][N];
int d[N],tag[N],book[N],f[N];
int n,m;
void work(int x)
{
    memset(d,63,sizeof(d));
    memset(book,0,sizeof(book));
    memset(f,0,sizeof(f));
    d[x]=0;
    for(int i=1;i<=n;i++)
    {
        int minx=2*1e9,t=0;    
        for(int j=1;j<=n;j++)
            if(!book[j]&&d[j]<minx) minx=d[j],t=j;    
        book[t]=1;
        for(int j=1;j<=n;j++)
            if(!book[j])
            {
                if(d[j]>d[t]+map[t][j]) d[j]=d[t]+map[t][j],f[j]=t;
                else if(d[j]==d[t]+map[t][j]) f[j]=0;
            }
    }
//    printf("\n");
    for(int i=1;i<=n;i++) if(f[i]&&f[i]!=x) tag[f[i]]=1;
//    for(int i=1;i<=n;i++) printf("%d ",f[i]);
//    printf("\n");
}
int main()
{
    freopen("city.in","r",stdin);
    freopen("city.out","w",stdout);
    memset(map,63,sizeof(map));
    scanf("%d %d",&n,&m);
    int a,b,c;
    for(int i=1;i<=m;i++)
    {
        scanf("%d %d %d",&a,&b,&c);
        map[a][b]=map[b][a]=min(map[a][b],c);
    }
    for(int i=1;i<=n;i++) work(i);
    int flag=0;
    for(int i=1;i<=n;i++)
    {
        if(tag[i]) flag=1,printf("%d ",i);
    }
    if(flag==0) printf("No important cities.\n");
    return 0;    
}

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