【Heap-Dijkstra】【分层图】bzoj2763 [JLOI2011]飞行路线

 1 #include<cstdio>
 2 #include<queue>
 3 #include<cstring>
 4 #include<algorithm>
 5 using namespace std;
 6 int n,m,k,sta,end,x,y,z,ans=2147483647;
 7 struct Point{int d,u;Point(const int &a,const int &b){d=a;u=b;}Point(){}};
 8 bool operator < (const Point &a,const Point &b){return a.d>b.d;}
 9 priority_queue<Point>q;
10 bool vis[110001];
11 int d[110001],first[2100001],next[2100001],v[2100001],w[2100001],en;
12 void AddEdge(const int &U,const int &V,const int &W)
13 {v[++en]=V; w[en]=W; next[en]=first[U]; first[U]=en;}
14 void dijkstra(const int &s)
15 {
16     memset(vis,false,sizeof(vis));
17     memset(d,0x7f,sizeof(d)); d[s]=0;
18     q.push(Point(0,s));
19     while(!q.empty())
20       {
21           Point x=q.top(); q.pop();
22           if(!vis[x.u])
23             {
24                 vis[x.u]=true;
25                 for(int i=first[x.u];i;i=next[i])
26                   if(d[v[i]]>d[x.u]+w[i])
27                     {
28                       d[v[i]]=d[x.u]+w[i];
29                       q.push(Point(d[v[i]],v[i]));
30                     }
31             }
32       }
33 }
34 int main()
35 {
36     scanf("%d%d%d%d%d",&n,&m,&k,&sta,&end);
37     for(int i=1;i<=m;i++)
38       {
39         scanf("%d%d%d",&x,&y,&z);
40         AddEdge(x,y,z);
41         AddEdge(y,x,z);
42         for(int j=1;j<=k;j++)
43           {
44               AddEdge(x+(j-1)*n,y+j*n,0);
45               AddEdge(y+(j-1)*n,x+j*n,0);
46               AddEdge(x+j*n,y+j*n,z);
47               AddEdge(y+j*n,x+j*n,z);
48           }
49       }
50     dijkstra(sta);
51     for(int i=0;i<=k;i++) ans=min(ans,d[end+i*n]);
52     printf("%d\n",ans);
53     return 0;
54 }