PAT-1018 Public Bike Management (30)

直接用dijkstra求取，只能拿到22,四个case过不了

#include<stdio.h>
#include<stack>
using namespace std;

int bike_count[510];
int bike_sum[510];
int bike_sum_num[510];
int map[510][510];
bool visited[510];
int d[510];
int pre[510];
int Max=0xffffffff>>1;
//max=max>>1;

int findMin(int n)
{
    int min=Max,index=-1;
    for(int i=0;i<=n;i++)
    {
      if(!visited[i]&&d[i]<min)
      {
          min=d[i];
          index=i;
      }
    }
    return index;
} 

int main()
{
     int maxc,n,sp,m;
     int a,b,val;
     freopen("1018-in.txt","r",stdin);
     freopen("1018-out.txt","w",stdout);
     while(scanf("%d%d%d%d",&maxc,&n,&sp,&m)!=EOF)
     {
       for(int i=0;i<=n;i++)//init map
        {
          for(int j=0;j<=n;j++)
          {
             map[i][j]=Max;
          }
          visited[i]=false;
          d[i]=Max;
          bike_sum[i]=0;
          bike_sum_num[i]=0;
          pre[i]=0;
        }
        bike_count[0]=0;
        for(int i=1;i<=n;i++)
        {
          scanf("%d",&bike_count[i]);
        }

        for(int i=0;i<m;i++)
        {
          scanf("%d%d%d",&a,&b,&val);
          map[a][b]=map[b][a]=val;
        }

        //begin dijkstra
        int index;
        d[0]=0;
        pre[0]=-1;
         while(true)
         {
            index=findMin(n);
            //for(int s=0;s<n;s++)
             // printf("%d ",d[s]);
            //("\n");
            visited[index]=true;
            //printf("index=%d\n",index);
            if(index==-1)
              break;
            for(int i=0;i<=n;i++)
            {
              if(map[i][index]!=Max&&d[i]>d[index]+map[index][i])
              {
                 d[i]=d[index]+map[index][i];
                 bike_sum[i]=bike_sum[index]+bike_count[i];
                 bike_sum_num[i]=bike_sum_num[index]+1;
                 pre[i]=index;
                 //printf( "0 i=%d,index=%d %d\n",i,index,bike_sum[i]);
              }
              else if(map[i][index]!=Max&&d[i]==d[index]+map[index][i])
              {
                 double a=(bike_sum[i]/(bike_sum_num[i]*1.0));
                 double b=(bike_sum[index]+bike_count[i])/((bike_sum_num[index]+1)*1.0);
                 //printf("%lf %lf\n",a,b);
                 if(a>maxc/2.0&&b>=maxc/2.0&&a>b)
                 {
                      d[i]=d[index]+map[index][i];
                      bike_sum[i]=bike_sum[index]+bike_count[i];
                      bike_sum_num[i]=bike_sum_num[index]+1;
                      pre[i]=index;
                      //printf("1 i=%d,index=%d,%d\n",i,index,bike_sum[i]);
                 }
                 if(a<maxc/2.0&&b<=maxc/2.0&&a<b)
                 {
                      d[i]=d[index]+map[index][i];
                      bike_sum[i]=bike_sum[index]+bike_count[i];
                      bike_sum_num[i]=bike_sum_num[index]+1;
                      pre[i]=index;
                      //printf("2 i=%d,index=%d,%d\n",i,index,bike_sum[i]);
                 }
                 if(a<maxc/2.0&&b>=maxc/2.0)
                 {
                      d[i]=d[index]+map[index][i];
                      bike_sum[i]=bike_sum[index]+bike_count[i];
                      bike_sum_num[i]=bike_sum_num[index]+1;
                      pre[i]=index;
                      //printf("3 i=%d,index=%d,%d\n",i,index,bike_sum[i]);
                 }
                 /*if(b==maxc/2.0)
                 {
                      d[i]=d[index]+map[index][i];
                      bike_sum[i]=bike_sum[index]+bike_count[i];
                      bike_sum_num[i]=bike_sum_num[index]+1;
                      pre[i]=index;
                 }*/
                 //printf("4 i=%d,index=%d,%d\n",i,index,bike_sum[i]);
              }
            }
         }//while(true)
         //printf("%d\n",bike_sum[sp]);
         //printf("%d\n",bike_sum_num[sp]);
          int mod=bike_sum_num[sp]*maxc/2-bike_sum[sp];
          printf("%d ",mod>=0?mod:0);
          int p=sp;
          stack<int> path;
          path.push(sp);
          while(true)
          {
             p=pre[p];
             if(p==-1)
               break;
             path.push(p);
          }
          while(!path.empty())
          {
              printf("%d",path.top());
              if(path.size()!=1)
               printf("->");
              path.pop();
          }
          printf(" %d\n",mod<=0?0-mod:0);
     }
    return 0;
}

网上找了一下，发现一个坑，那就是后面的站点的车辆不能运送会前面的站点，所以会还有四个测试数据没有通过，需要DIJSKSTRA+DFS来实现。需要保存所有的路径下来。

后续再补上。