图的第k短路

  1 #include<iostream>
  2 #include<cstdio>
  3 #include<cstring>
  4 #include<cstdlib>
  5 #include<cmath>
  6 #include<ctime>
  7 #include<algorithm>
  8 #include<queue>
  9 #define MAXN 20100
 10 #define INF 1000100000
 11 #define pii pair<int,int> 
 12 using namespace std;
 13 struct node{int y,next,v;}e1[MAXN],e2[MAXN];
 14 struct node2
 15 {
 16     int f,g,id;    
 17     friend bool operator < (node2 a,node2 b)
 18     {
 19         return a.f>b.f;
 20     }
 21 };
 22 int n,m,k,len1,len2,Link1[MAXN],Link2[MAXN],dis[MAXN],vis[MAXN],tim[MAXN],ans[MAXN];
 23 priority_queue<node2>Q;
 24 inline int read()
 25 {
 26     int x=0,f=1;  char ch=getchar();
 27     while(!isdigit(ch))  {if(ch==‘-‘)  f=-1;  ch=getchar();}
 28     while(isdigit(ch))  {x=x*10+ch-‘0‘;  ch=getchar();}
 29     return x*f;
 30 }
 31 void insert(int xx,int yy,int vv)
 32 {
 33     e1[++len1].next=Link1[xx];
 34     Link1[xx]=len1;
 35     e1[len1].y=yy;
 36     e1[len1].v=vv;              
 37     e2[++len2].next=Link2[yy];
 38     Link2[yy]=len2;
 39     e2[len2].y=xx;
 40     e2[len2].v=vv;              
 41 }
 42 void SPFA()
 43 {
 44     priority_queue<int,vector< int >,greater< int > >q;
 45     memset(dis,50,sizeof(dis));
 46     dis[1]=0,vis[1]=1,q.push(1);
 47     while(!q.empty())
 48     {
 49         int tn=q.top();
 50         vis[tn]=0;
 51         q.pop();
 52         for(int i=Link2[tn];i;i=e2[i].next)
 53         {
 54             int tmp=e2[i].y;
 55             if(dis[tmp]>dis[tn]+e2[i].v)
 56             {
 57                 dis[tmp]=dis[tn]+e2[i].v;
 58                 if(!vis[tmp])
 59                 {
 60                     vis[tmp]=1;
 61                     q.push(tmp);
 62                 }
 63             }
 64         }
 65     }
 66 }
 67 void Astar()
 68 {
 69     if(dis[n]==INF)  return;
 70     node2 temp;  temp.g=0,temp.f=dis[n],temp.id=n;
 71     Q.push(temp);
 72     while(!Q.empty())
 73     {
 74         temp=Q.top(); Q.pop();
 75         if(temp.id==1)  {ans[++ans[0]]=temp.f;  if(ans[0]>k)  return;}  
 76         for(int i=Link1[temp.id];i;i=e1[i].next)
 77         {
 78             node2 opt;
 79             opt.g=temp.g+e1[i].v;
 80             opt.f=opt.g+dis[e1[i].y];
 81             opt.id=e1[i].y;
 82             Q.push(opt);
 83         }
 84     }
 85 }
 86 int main()
 87 {
 88     n=read();  m=read();  k=read();
 89     for(int i=1;i<=m;i++)
 90     {
 91         int x=read(),y=read(),v=read();
 92         insert(x,y,v);
 93     }
 94     SPFA();
 95     Astar();
 96     for(int i=1;i<=k;i++)
 97     {
 98         if(!ans[i])  printf("-1\n");
 99         else printf("%d\n",ans[i]);
100     }
101     return 0;
102 }