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]); 
            //("
");
            visited[index]=true;
            //printf("index=%d
",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
",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
",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
",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
",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
",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
",i,index,bike_sum[i]);
              }
            }
         }//while(true)
         //printf("%d
",bike_sum[sp]); 
         //printf("%d
",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
",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。

==================

这次试用dijkstra+dfs算法实现。可以拿到29分，据说测试数据9是大数据，用现在方法写出的程序，时间复杂读比较大，dfs之后，还需要扫描所有出来的路径，这一步，本来可以在dfs的时候就完成的，但是由于回朔工地太差了，没有继续做下去。

// 1018a.cpp : 定义控制台应用程序的入口点。
//
#include "StdAfx.h"
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<iostream>
#include<vector>
using namespace std;

#define MAX 1010
int d[MAX];
int bike_count[MAX];
int map[MAX][MAX];
int maxInt=0xffffffff>>1;
bool visited[MAX];
bool vis[MAX];

int findMinIndex(int n)
{
    int min=maxInt,minIndex=-1;
    for(int i=0;i<=n;i++)
    {
      if(!visited[i]&&min>d[i])
      {
         min=d[i];
         minIndex=i;
      }
    }
    return minIndex;
}

struct Path
{
  vector<int> v;
  int bike_need;
  int before;
  int count;
};
Path p;
vector<Path> path;
int cmax,n,sp,m;
int a,b,tmp;

vector<int>::iterator it;
void dfs(int node,int dist,int n,int max_dist)
{
    //cout<<node<<" "<<dist<<" "<<n<<" "<<max_dist<<endl;
    vis[node]=true;
    if(dist>max_dist)
       return;
     p.v.push_back(node);
     p.count++;
    if(dist==max_dist)//lost node==sp
    {
      vector<int>::iterator it=p.v.begin();
      for(;it!=p.v.end();it++)
       {
          cout<<*it<<" ";
       }
       cout<<endl;
       if(node==sp)
          path.push_back(p);
       //p.v.clear()
     it=p.v.begin();
     for(;it!=p.v.end();it++)
     {
          if(*it==node)
          {
              p.v.erase(it);
              p.count--;
             cout<<"delete q"<<node<<endl;
              break;
          }
     }
       vis[node]=false;
       return;
    }

    for(int i=0;i<=n;i++)
    {  
      if(map[i][node]!=maxInt&&!vis[i])
      {
          //cout<<i<<" "<<endl;
          dist=dist+map[i][node];//
          dfs(i,dist,n,max_dist); 
          dist=dist-map[i][node];//
      } 
    }
     vis[node]=false;
     it=p.v.begin();
     for(;it!=p.v.end();it++)
     {
          if(*it==node)
          {
            p.v.erase(it);
            p.count--;
            cout<<"delete"<<node<<endl;
            break;//attention
          }
     }
}

void dfsg(int n,int max_dist)
{
     /*for(int i=0;i<=n;i++)
     {
        if(!vis[i])
           dfs(i,0,n,max_dist);
     }*/
     dfs(0,0,n,max_dist); 
}


int main()
{
   freopen("1018-in.txt","r",stdin);
   freopen("1018-out.txt","w",stdout);
   p.bike_need=0;
   p.count=0;
   p.before=0;
    while(cin>>cmax>>n>>sp>>m)
    {
       memset(map,0,sizeof(int)*MAX*MAX);
       d[0]=0;
       map[0][0]=0;
      /* for(int i=1;i<=n;i++)
       {
         cin>>bike_count[i];
         d[i]=maxInt;
         visited[i]=false;
         map[i][i]=maxInt;
         vis[i]=false;
       }*/
       for(int i=0;i<=n;i++)//map初始化为无穷maxInt 
       {
         for(int j=0;j<=n;j++)
         {
            map[i][j]=maxInt;
         } 
         if(i!=0)
         {
             cin>>bike_count[i];
             d[i]=maxInt;
             visited[i]=false;
             map[i][i]=maxInt;
             vis[i]=false;
         }
       }
       for(int j=0;j<m;j++)
       {
          cin>>a>>b>>tmp;
          map[a][b]=map[b][a]=tmp;
       }
       int index;
       while(true)
       {
          index=findMinIndex(n);
         // cout<<index<<endl;
          if(index==-1)
              break;
          for(int i=1;i<=n;i++)
          {
             if(!visited[index]&&map[index][i]!=maxInt)//是否需要visited 
             {
                 if(d[i]>d[index]+map[index][i])
                    d[i]=d[index]+map[index][i];
             }
          }
          visited[index]=true;       
       }
       
       cout<<d[sp]<<endl;
       

       dfsg(n,d[sp]);  
       bike_count[0]=cmax/2;
       vector<Path>::iterator it=path.begin();
       int result=-1;
       int result_need=0;
       int result_before=0;
       for(int s=0;s<path.size();s++)
       {
           Path p=*(it+s);
           int bike_need=0;
           int bike_before=0;

           for(int j=0;j<p.v.size();j++)
           {
               int node=p.v[j];
               if(bike_count[node]>=cmax/2)
                   bike_before+=(bike_count[node]-cmax/2);
               else
               {
                   if(bike_before+bike_count[node]>=cmax/2)
                   {
                       int temp=(bike_before+bike_count[node]-cmax/2);
                       bike_before=temp;           
                   }
                   else
                   {
                       bike_need+=(cmax/2-bike_before-bike_count[node]);
                       bike_before=0;
                   }
               }
           }
           if(result==-1)
            {
                result=s;
                result_need=bike_need;
                result_before=bike_before;
           }
           else
           {
               if(result_need>bike_need)
               {
                    result=s;
                    result_need=bike_need;
                    result_before=bike_before;
               }
               else if(result_need==bike_need)
               {
                   if(result_before>bike_before)
                   {
                           result=s;
                        result_need=bike_need;
                        result_before=bike_before;
                   }
               }
           }
       }
       //测试数据9,是大数据测试点，过不了
      cout<<result_need<<" ";
      p=path[result];
      for(int i=0;i<p.v.size();i++)
      {
          cout<<p.v[i];
          if(i!=p.v.size()-1)
              cout<<"->";
      }
      cout<<" "<<result_before<<endl;
    }
}