POJ 2449Remmarguts' Date K短路模板 SPFA+A*

K短路模板，A*+SPFA求K短路。A*中h的求法为在反图中做SPFA，求出到T点的最短路，极为估价函数h（这里不再是估价，而是准确值），然后跑A*，从S点开始（此时为最短路），然后把与S点能达到的点加入堆中，维护堆，再从堆顶取当前g值最小的点(此时为第2短路)，再添加相邻的点放入堆中，依此类推······保证第k次从堆顶取到的点都是第k短路（至于为什么，自己想）其实就是A*算法，这里太啰嗦了

　1 #include<queue>
  2 #include<cstdio>
  3 #include<cstring>
  4 #include<algorithm>
  5 using namespace std;
  6 int v[100010],v2[100010],c[100010],c2[100010],s,t,k,duin;
  7 int n,m,point[1010],next[100010],cnt=0,point2[1010],next2[100010],cnt2=0;
  8 int dist[1010],vis[1010],cont[1010],duig[1000100],duiu[1000100],duif[1000100];
  9 queue<int>q;
 10 void insect(int u,int e,int z)
 11 {cnt++; next[cnt]=point[u]; point[u]=cnt; v[cnt]=e; c[cnt]=z;}
 12 void insect2(int u,int e,int z)
 13 {cnt2++; next2[cnt2]=point2[u]; point2[u]=cnt2; v2[cnt2]=e; c2[cnt2]=z;}
 14 void spfa()
 15 {    int e,mp; while (!q.empty()) q.pop();
 16     memset(vis,0,sizeof(vis));
 17     memset(dist,127,sizeof(dist));
 18     dist[t]=0; vis[t]=1; q.push(t);
 19     while (!q.empty())
 20     {
 21         e=q.front(); q.pop(); vis[e]=0;
 22         for (mp=point2[e];mp!=0;mp=next2[mp])
 23         {
 24             if (dist[v2[mp]]>dist[e]+c2[mp])
 25             {
 26                 dist[v2[mp]]=dist[e]+c2[mp];
 27                 if (vis[v2[mp]]==0)
 28                 {
 29                     vis[v2[mp]]=1;
 30                     q.push(v2[mp]);
 31                 }
 32             }
 33         }
 34     }
 35 }
 36 void swap(int &a,int &b){int c=a;a=b;b=c;}
 37 void popdui()
 38 {
 39     duif[1]=duif[duin]; duiu[1]=duiu[duin]; duig[1]=duig[duin];
 40     duin--;
 41     int i=1;
 42     while (i<duin)
 43     {
 44         if (((duif[i]<duif[i*2])||(i*2>duin))&&((duif[i]<duif[i*2+1])||(i*2+1>duin)))
 45          return;
 46         if (i*2+1<=duin)
 47          if (duif[i*2+1]<duif[i*2])
 48          {    swap(duif[i],duif[i*2+1]);swap(duig[i],duig[i*2+1]);
 49              swap(duiu[i],duiu[i*2+1]);i=i*2+1;}
 50          else
 51          {     swap(duif[i],duif[i*2]);swap(duig[i],duig[i*2]);
 52              swap(duiu[i],duiu[i*2]);i=i*2;}
 53         else
 54          {     swap(duif[i],duif[i*2]);swap(duig[i],duig[i*2]);
 55              swap(duiu[i],duiu[i*2]);i=i*2;}
 56     }
 57 }
 58 void puss(int vv,int gg,int ff)
 59 {
 60     duin++;
 61     duiu[duin]=vv;duig[duin]=gg;duif[duin]=ff;
 62     int i=duin;
 63     while (i>1)
 64     {
 65         if (duif[i]<duif[i/2])
 66         {
 67             swap(duif[i],duif[i/2]);
 68             swap(duiu[i],duiu[i/2]);
 69             swap(duig[i],duig[i/2]);
 70         }
 71         else return;
 72         i=i/2;
 73     }
 74 }
 75 int astar()
 76 {
 77     memset(cont,0,sizeof(cont));
 78     memset(duif,0,sizeof(duif));
 79     memset(duiu,0,sizeof(duiu));
 80     memset(duig,0,sizeof(duig));
 81     if (s==t) k++; cnt=0;
 82     int f,u,now,i; duin=1;duif[1]=dist[s];duiu[1]=s;duig[1]=0;
 83     while (duin>0)
 84     {
 85         f=duif[1]; u=duiu[1]; now=duig[1];
 86         popdui();
 87         if (u==t) cnt++;
 88         if (cnt==k) return now;
 89         for (i=point[u];i!=0;i=next[i])
 90         {
 91             puss(v[i],now+c[i],now+c[i]+dist[v[i]]);
 92         }
 93     }
 94     return -1;
 95 }
 96 int main()
 97 {
 98     int i,j,a,b,cc;
 99     while (scanf("%d %d\n",&n,&m)!=EOF)
100     {
101         memset(point,0,sizeof(point)); memset(point2,0,sizeof(point2));
102         memset(next,0,sizeof(next)); memset(next2,0,sizeof(next2));
103         memset(v,0,sizeof(v)); memset(v2,0,sizeof(v2));
104         memset(c,0,sizeof(c)); memset(c2,0,sizeof(c2));
105         cnt=0; cnt2=0;
106         for (i=1;i<=m;++i)
107         {
108             scanf("%d %d %d\n",&a,&b,&cc);
109             insect(a,b,cc); insect2(b,a,cc);
110         } scanf("%d %d %d\n",&s,&t,&k);
111         spfa();
112         printf("%d\n",astar()); break;
113     }
114     return 0;
115 }

 

posted @ 2015-12-13 21:14  abclzr  阅读(277)  评论(0)  编辑  收藏  举报