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>
 #include<cstring>
 #include<algorithm>
 using namespace std;
 int v[],v2[],c[],c2[],s,t,k,duin;
 int n,m,point[],next[],cnt=,point2[],next2[],cnt2=;
 int dist[],vis[],cont[],duig[],duiu[],duif[];
 queue<int>q;
 void insect(int u,int e,int z)
 {cnt++; next[cnt]=point[u]; point[u]=cnt; v[cnt]=e; c[cnt]=z;}
 void insect2(int u,int e,int z)
 {cnt2++; next2[cnt2]=point2[u]; point2[u]=cnt2; v2[cnt2]=e; c2[cnt2]=z;}
 void spfa()
 {    int e,mp; while (!q.empty()) q.pop();
     memset(vis,,sizeof(vis));
     memset(dist,,sizeof(dist));
     dist[t]=; vis[t]=; q.push(t);
     while (!q.empty())
     {
         e=q.front(); q.pop(); vis[e]=;
         for (mp=point2[e];mp!=;mp=next2[mp])
         {
             if (dist[v2[mp]]>dist[e]+c2[mp])
             {
                 dist[v2[mp]]=dist[e]+c2[mp];
                 if (vis[v2[mp]]==)
                 {
                     vis[v2[mp]]=;
                     q.push(v2[mp]);
                 }
             }
         }
     }
 }
 void swap(int &a,int &b){int c=a;a=b;b=c;}
 void popdui()
 {
     duif[]=duif[duin]; duiu[]=duiu[duin]; duig[]=duig[duin];
     duin--;
     int i=;
     while (i<duin)
     {
         if (((duif[i]<duif[i*])||(i*>duin))&&((duif[i]<duif[i*+])||(i*+>duin)))
          return;
         if (i*+<=duin)
          if (duif[i*+]<duif[i*])
          {    swap(duif[i],duif[i*+]);swap(duig[i],duig[i*+]);
              swap(duiu[i],duiu[i*+]);i=i*+;}
          else
          {     swap(duif[i],duif[i*]);swap(duig[i],duig[i*]);
              swap(duiu[i],duiu[i*]);i=i*;}
         else
          {     swap(duif[i],duif[i*]);swap(duig[i],duig[i*]);
              swap(duiu[i],duiu[i*]);i=i*;}
     }
 }
 void puss(int vv,int gg,int ff)
 {
     duin++;
     duiu[duin]=vv;duig[duin]=gg;duif[duin]=ff;
     int i=duin;
     while (i>)
     {
         if (duif[i]<duif[i/])
         {
             swap(duif[i],duif[i/]);
             swap(duiu[i],duiu[i/]);
             swap(duig[i],duig[i/]);
         }
         else return;
         i=i/;
     }
 }
 int astar()
 {
     memset(cont,,sizeof(cont));
     memset(duif,,sizeof(duif));
     memset(duiu,,sizeof(duiu));
     memset(duig,,sizeof(duig));
     if (s==t) k++; cnt=;
     int f,u,now,i; duin=;duif[]=dist[s];duiu[]=s;duig[]=;
     while (duin>)
     {
         f=duif[]; u=duiu[]; now=duig[];
         popdui();
         if (u==t) cnt++;
         if (cnt==k) return now;
         for (i=point[u];i!=;i=next[i])
         {
             puss(v[i],now+c[i],now+c[i]+dist[v[i]]);
         }
     }
     return -;
 }
 int main()
 {
     int i,j,a,b,cc;
     while (scanf("%d %d\n",&n,&m)!=EOF)
     {
         memset(point,,sizeof(point)); memset(point2,,sizeof(point2));
         memset(next,,sizeof(next)); memset(next2,,sizeof(next2));
         memset(v,,sizeof(v)); memset(v2,,sizeof(v2));
         memset(c,,sizeof(c)); memset(c2,,sizeof(c2));
         cnt=; cnt2=;
         for (i=;i<=m;++i)
         {
             scanf("%d %d %d\n",&a,&b,&cc);
             insect(a,b,cc); insect2(b,a,cc);
         } scanf("%d %d %d\n",&s,&t,&k);
         spfa();
         printf("%d\n",astar()); break;
     }
     return ;
 }