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。

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

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;
}
}