A*算法求K短路模板 POJ 2449

#include<cstdio>
#include<queue>
#include<cstring>
using namespace std;
const int maxn=2e6+5;
struct asd{
    int from,to,next,val;
}b[maxn],b2[maxn];
int head[maxn],tot=1;
int h2[maxn],t2=1;
int n,m;
void ad(int aa,int bb,int cc){
    b[tot].from=aa;
    b[tot].to=bb;
    b[tot].val=cc;
    b[tot].next=head[aa];
    head[aa]=tot++;
}
void ad2(int aa,int bb,int cc){
    b2[t2].from=aa;
    b2[t2].to=bb;
    b2[t2].val=cc;
    b2[t2].next=h2[aa];
    h2[aa]=t2++;
}
struct jie{
    int num,dis;
    jie(int aa=0,int bb=0){
        num=aa,dis=bb;
    }
    bool operator < (const jie& A) const{
        return dis>A.dis;
    }
};
priority_queue<jie> q;
int dis[maxn];
bool vis[maxn];
void DIJ(int xx){
    dis[xx]=0;
    q.push(jie(xx,0));
    while(!q.empty()){
        int now=q.top().num;
        q.pop();
        if(vis[now]) continue;
        vis[now]=1;
        for(int i=head[now];i!=-1;i=b[i].next){
            int u=b[i].to;
            if(dis[u]>dis[now]+b[i].val){
                dis[u]=dis[now]+b[i].val;
                q.push(jie(u,dis[u]));
            }
        }
    }
}
struct as{
    int qd,hx,gx;
    as(int aa=0,int bb=0,int cc=0){
        qd=aa,hx=bb,gx=cc;
    }
    bool operator < (const as& A) const{
        return hx+gx>A.hx+A.gx;
    }
};
int cnt[maxn];
priority_queue<as> qq;
int Astar(int s,int t,int k){
    if(dis[s]==0x3f3f3f3f) return -1;
    qq.push(as(s,dis[s],0));
    while(!qq.empty()){
        int nqd=qq.top().qd,nhx=qq.top().hx,ngx=qq.top().gx;
        qq.pop();
        cnt[nqd]++;
        if(cnt[nqd]==k && nqd==t) return ngx;
        if(cnt[nqd]>k) continue;
        for(int i=h2[nqd];i!=-1;i=b2[i].next){
            int u=b2[i].to;
            qq.push(as(u,dis[u],ngx+b2[i].val));
        }
    }
    return -1;
}
int main(){
    memset(dis,0x3f,sizeof(dis));
    memset(head,-1,sizeof(head));
    memset(h2,-1,sizeof(h2));
    scanf("%d%d",&n,&m);
    for(int i=1;i<=m;i++){
        int aa,bb,cc;
        scanf("%d%d%d",&aa,&bb,&cc);
        ad2(aa,bb,cc);
        ad(bb,aa,cc);
    }
    int s,t,k;
    scanf("%d%d%d",&s,&t,&k);
    if(s==t) ++k;
    DIJ(t);
    printf("%d
",Astar(s,t,k));
    return 0;
}