网络流24题----15汽车加油行驶问题

Posted 2020-08-28 №〓→龙光←

 

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喜闻乐见的分层图最短路，注意到了加油站是强制要加满油的

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  1 #include<iostream>
  2 #include<cstdio>
  3 #include<algorithm>
  4 #include<vector>
  5 #include<cstdlib>
  6 #include<cmath>
  7 #include<cstring>
  8 using namespace std;
  9 #define maxn 110
 10 #define SIZE 1000000
 11 #define llg long long 
 12 #define inf (llg)1e16
 13 #define yyj(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);
 14 
 15 llg n,m,k,A,B,C,dis[maxn*maxn][15],bj[maxn*maxn][maxn],se[maxn*maxn],head,tail;
 16 llg p[5][4];
 17 vector<llg>a[maxn*maxn],val[maxn*maxn];
 18 
 19 llg num(llg x,llg y){return (x-1)*n+y;}
 20 
 21 void link(llg x,llg y,llg z){a[x].push_back(y),val[x].push_back(z);}
 22 
 23 struct node
 24 {
 25     llg x,y;
 26 }dl[SIZE+5];
 27 
 28 void init()
 29 {
 30     p[1][0]=1,p[2][1]=1,p[3][0]=-1,p[4][1]=-1;
 31     cin>>n>>k>>A>>B>>C;
 32     for (llg i=1;i<=n*n;i++) scanf("%lld",&se[i]);
 33     for (llg i=1;i<=n;i++)
 34         for (llg j=1;j<=n;j++)
 35             for (llg w=1;w<=4;w++)
 36             {
 37                 llg x=i+p[w][0],y=j+p[w][1];
 38                 if (x>n || x<1 || y>n || y<1) continue;
 39                 if (w<=2) link(num(i,j),num(x,y),0);
 40                 else link(num(i,j),num(x,y),B);
 41             }
 42     for (llg i=1;i<=n*n;i++) for (llg j=0;j<=k;j++) dis[i][j]=inf;
 43     tail=1,head=0;
 44     dl[1].x=1;dl[1].y=k; dis[1][k]=0;
 45 }
 46 
 47 void spfa()
 48 {
 49     llg x,v,y,w;
 50     do
 51     {
 52         head%=SIZE; head++;
 53         x=dl[head].x,y=dl[head].y;
 54         w=a[x].size(); bj[x][y]=0;
 55         if  (se[x] && y!=k)
 56         {
 57             if (dis[x][y]+A<dis[x][k])
 58             {
 59                 dis[x][k]=dis[x][y]+A;
 60                 if (!bj[x][k])
 61                 {
 62                     bj[x][k]=1;
 63                     tail%=SIZE; tail++;
 64                     dl[tail].x=x,dl[tail].y=k;
 65                 }
 66             }
 67             continue;
 68         }
 69         if (y!=0)
 70         {
 71             for (llg i=0;i<w;i++)
 72             {
 73                 v=a[x][i];
 74                 if (dis[v][y-1]>dis[x][y]+val[x][i])
 75                 {
 76                     dis[v][y-1]=dis[x][y]+val[x][i];
 77                     if (!bj[v][y-1])
 78                     {
 79                         bj[v][y-1]=1;
 80                         tail%=SIZE; tail++;
 81                         dl[tail].x=v;dl[tail].y=y-1;
 82                     }
 83                 }
 84             }
 85         }
 86         if (y!=k && se[x]==0)
 87         {
 88             if (dis[x][k]>dis[x][y]+C+A)
 89             {
 90                 dis[x][k]=dis[x][y]+C+A;
 91                 if (!bj[x][k])
 92                 {
 93                     bj[x][k]=1;
 94                     tail%=SIZE; tail++;
 95                     dl[tail].x=x,dl[tail].y=k;
 96                 }
 97             }
 98         }
 99     }while(head!=tail);
100 }
101 
102 int main()
103 {
104     yyj("car");
105     init();
106 //    k--;
107     spfa();
108     llg ans=inf;
109     for (llg i=0;i<=k;i++) ans=min(ans,dis[n*n][i]);
110     cout<<ans;
111     return 0;
112 }