D. Made In Heaven

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K短路A*算法

#include<bits/stdc++.h>
using namespace std;
#define INF 0xffffff
const int MAXN = 2e6;
typedef long long ll;
struct node
{
    ll to;
    ll val;
    ll next;
};
struct node2
{
    ll to;
    ll g,f;
    bool operator<(const node2 &r ) const  
    {  
        if(r.f==f)  
            return r.g<g;  
        return r.f<f;  
    }   
};
node edge[MAXN],edge2[MAXN];
ll n,m,s,t,k,cnt,cnt2,ans;
ll dis[1010],visit[1010],head[1010],head2[1010];
void init()
{
    memset(head,-1,sizeof(head));
    memset(head2,-1,sizeof(head2));
    cnt=cnt2=1;
}
void addedge(ll from,ll to,ll val)
{
    edge[cnt].to=to;
    edge[cnt].val=val;
    edge[cnt].next=head[from];
    head[from]=cnt++;
}
void addedge2(ll from,ll to,ll val)
{
    edge2[cnt2].to=to;
    edge2[cnt2].val=val;
    edge2[cnt2].next=head2[from];
    head2[from]=cnt2++;
}
bool spfa(ll s,ll n,ll head[],node edge[],ll dist[])  
{  
    queue<int>Q1;  
    ll inq[1010];  
    for(ll i=0;i<=n;i++)  
    {  
        dis[i]=INF;  
        inq[i]=0;  
    }  
    dis[s]=0;  
    Q1.push(s);  
    inq[s]++;  
    while(!Q1.empty())  
    {  
        ll q=Q1.front();  
        Q1.pop();  
        inq[q]--;  
        if(inq[q]>n)
            return false;  
        ll k=head[q];  
        while(k>=0)  
        {  
            if(dist[edge[k].to]>dist[q]+edge[k].val)  
            {  
                dist[edge[k].to]=edge[k].val+dist[q];  
                if(!inq[edge[k].to])  
                {  
                    inq[edge[k].to]++;  
                    Q1.push(edge[k].to);  
                }  
            }  
            k=edge[k].next;  
        }  
    }  
    return true;  
}
ll A_star(ll s,ll t,ll n,ll k,ll head[],node edge[],ll dist[]) 
{  
    node2 e,ne;  
    ll cnt=0;  
    priority_queue<node2>Q;  
    if(s==t)
        k++;  
    if(dis[s]==INF)  
        return -1;  
    e.to=s;  
    e.g=0;  
    e.f=e.g+dis[e.to];  
    Q.push(e);  

    while(!Q.empty())  
    {  
        e=Q.top();  
        Q.pop();  
        if(e.to==t)//找到一条最短路径  
        {  
            cnt++;  
        }  
        if(cnt==k)//找到k短路  
        {  
            return e.g;  
        }  
        for(ll i=head[e.to]; i!=-1; i=edge[i].next)  
        {  
            ne.to=edge[i].to;  
            ne.g=e.g+edge[i].val;  
            ne.f=ne.g+dis[ne.to];  
            Q.push(ne);  
        }  
    }  
    return -1;  
}  
int main()
{
    while(~scanf("%d%d",&n,&m))
    {
        init();
        scanf("%lld%lld%lld",&s,&t,&k);
        ll tt;
        cin>>tt;
        for(ll i=1;i<=m;i++)
        {
            ll a,b,c;
            scanf("%lld%lld%lld",&a,&b,&c);
            addedge(a,b,c);
            addedge2(b,a,c);
        }
        spfa(t,n,head2,edge2,dis);
        ans=A_star(s,t,n,k,head,edge,dis);
        if(ans>tt || ans == -1) puts("Whitesnake!");     
        else puts("yareyaredawa");   
     }

    return 0;
}