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[100010],v2[100010],c[100010],c2[100010],s,t,k,duin;
int n,m,point[1010],next[100010],cnt=0,point2[1010],next2[100010],cnt2=0;
int dist[1010],vis[1010],cont[1010],duig[1000100],duiu[1000100],duif[1000100];
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,0,sizeof(vis));
    memset(dist,127,sizeof(dist));
    dist[t]=0; vis[t]=1; q.push(t);
    while (!q.empty())
    {
        e=q.front(); q.pop(); vis[e]=0;
        for (mp=point2[e];mp!=0;mp=next2[mp])
        {
            if (dist[v2[mp]]>dist[e]+c2[mp])
            {
                dist[v2[mp]]=dist[e]+c2[mp];
                if (vis[v2[mp]]==0)
                {
                    vis[v2[mp]]=1;
                    q.push(v2[mp]);
                }
            }
        }
    }
}
void swap(int &a,int &b){int c=a;a=b;b=c;}
void popdui()
{
    duif[1]=duif[duin]; duiu[1]=duiu[duin]; duig[1]=duig[duin];
    duin--;
    int i=1;
    while (i<duin)
    {
        if (((duif[i]<duif[i*2])||(i*2>duin))&&((duif[i]<duif[i*2+1])||(i*2+1>duin)))
         return;
        if (i*2+1<=duin)
         if (duif[i*2+1]<duif[i*2])
         {    swap(duif[i],duif[i*2+1]);swap(duig[i],duig[i*2+1]);
             swap(duiu[i],duiu[i*2+1]);i=i*2+1;}
         else
         {     swap(duif[i],duif[i*2]);swap(duig[i],duig[i*2]);
             swap(duiu[i],duiu[i*2]);i=i*2;}
        else
         {     swap(duif[i],duif[i*2]);swap(duig[i],duig[i*2]);
             swap(duiu[i],duiu[i*2]);i=i*2;}
    }
}
void puss(int vv,int gg,int ff)
{
    duin++;
    duiu[duin]=vv;duig[duin]=gg;duif[duin]=ff;
    int i=duin;
    while (i>1)
    {
        if (duif[i]<duif[i/2])
        {
            swap(duif[i],duif[i/2]);
            swap(duiu[i],duiu[i/2]);
            swap(duig[i],duig[i/2]);
        }
        else return;
        i=i/2;
    }
}
int astar()
{
    memset(cont,0,sizeof(cont));
    memset(duif,0,sizeof(duif));
    memset(duiu,0,sizeof(duiu));
    memset(duig,0,sizeof(duig));
    if (s==t) k++; cnt=0;
    int f,u,now,i; duin=1;duif[1]=dist[s];duiu[1]=s;duig[1]=0;
    while (duin>0)
    {
        f=duif[1]; u=duiu[1]; now=duig[1];
        popdui();
        if (u==t) cnt++;
        if (cnt==k) return now;
        for (i=point[u];i!=0;i=next[i])
        {
            puss(v[i],now+c[i],now+c[i]+dist[v[i]]);
        }
    }
    return -1;
}
int main()
{
    int i,j,a,b,cc;
    while (scanf("%d %d
",&n,&m)!=EOF)
    {
        memset(point,0,sizeof(point)); memset(point2,0,sizeof(point2));
        memset(next,0,sizeof(next)); memset(next2,0,sizeof(next2));
        memset(v,0,sizeof(v)); memset(v2,0,sizeof(v2));
        memset(c,0,sizeof(c)); memset(c2,0,sizeof(c2));
        cnt=0; cnt2=0;
        for (i=1;i<=m;++i)
        {
            scanf("%d %d %d
",&a,&b,&cc);
            insect(a,b,cc); insect2(b,a,cc);
        } scanf("%d %d %d
",&s,&t,&k);
        spfa();
        printf("%d
",astar()); break;
    }
    return 0;
}