Bus System

杭电1690

不理解

#include<stdio.h>
#include<iostream>
using namespace std;
#define maxint 0x7f7f7f7f7f7f7f7fLL
typedef __int64 LL;
LL mat[105][105];
LL cor[105];
LL l1,l2,l3,l4,c1,c2,c3,c4;
int n;
LL change(LL x)
{
    if(x<0) x=-x;
    if(x>0&&x<=l1) return c1;
    if(x>l1&&x<=l2) return c2;
    if(x>l2&&x<=l3) return c3;
    if(x>l3&&x<=l4) return c4;
    if(x>l4) return maxint;
}

void floyd()
{
    int i,j,k;
    for(k=1;k<=n;k++)
        for(i=1;i<=n;i++)
            for(j=1;j<=n;j++)
                if(mat[i][k]!=maxint&&mat[k][j]!=maxint)
                    if(mat[i][j]>mat[i][k]+mat[k][j])
                        mat[i][j]=mat[i][k]+mat[k][j];
}
int main()
{
    int t,i,j,m,cas=1;
    scanf("%d",&t);
    while(t--)
    {
        printf("Case %d:\n",cas++);
        scanf("%I64d %I64d %I64d %I64d %I64d %I64d %I64d %I64d",&l1,&l2,&l3,&l4,&c1,&c2,&c3,&c4);
        scanf("%d%d",&n,&m);
        for(i=1;i<=n;i++)
            scanf("%I64d",&cor[i]);
        for(i=1;i<=n;i++)
            for(j=i+1;j<=n;j++)
            {
                LL x=cor[i]-cor[j];
                mat[i][j]=mat[j][i]=change(x);
            }
     floyd();
     while(m--)
     {
         int x,y;
         scanf("%d%d",&x,&y);
         if(mat[x][y]!=maxint)
             printf("The minimum cost between station %d and station %d is %I64d.\n",x,y,mat[x][y]);
          else
              printf("Station %d and station %d are not attainable.\n",x,y);
     }
    }
    return 0;
}