POJ——2449 Remmarguts' Date

 1 #include<iostream>
 2 #include<queue>
 3 #include<cstring>
 4 #include<algorithm>
 5 #include<cmath>
 6 #include<cstdlib>
 7 #include<vector>
 8 #include<cstdio>
 9 #define il inline
10 #define ll long long
11 #define For(i,a,b) for(int (i)=(a);(i)<=(b);(i)++)
12 #define Bor(i,a,b) for(int (i)=(b);(i)>=(a);(i)--)
13 #define Max(a,b) ((a)>(b)?(a):(b))
14 #define Min(a,b) ((a)>(b)?(b):(a))
15 using namespace std;
16 const int N=200005,inf=233333333;
17 int s,t,n,m,k,w[N],W[N],dis[N],ans[N],tot;
18 int to[N],net[N],h[N],cnt1,To[N],Net[N],H[N],cnt2;
19 struct node{
20     int f,g,id;
21     bool operator<(const node a)const{return f>a.f;}
22 };
23 bool vis[N];
24 priority_queue<node>Q;
25 
26 il int gi(){
27     int a=0;char x=getchar();bool f=0;
28     while((x<‘0‘||x>‘9‘)&&x!=‘-‘)x=getchar();
29     if(x==‘-‘)x=getchar(),f=1;
30     while(x>=‘0‘&&x<=‘9‘)a=(a<<3)+(a<<1)+x-48,x=getchar();
31     return f?-a:a;
32 }
33 
34 il void add(int u,int v,int c){
35     to[++cnt1]=v,net[cnt1]=h[u],h[u]=cnt1,w[cnt1]=c;
36     To[++cnt2]=u,Net[cnt2]=H[v],H[v]=cnt2,W[cnt2]=c;
37 }
38 
39 il void spfa(){
40     queue<int>q;
41     For(i,1,n) dis[i]=inf;
42     dis[s]=0,vis[s]=1,q.push(s);
43     while(!q.empty()){
44         int u=q.front();vis[u]=0;q.pop();
45         for(int i=h[u];i;i=net[i])
46             if(dis[to[i]]>dis[u]+w[i]){
47                 dis[to[i]]=dis[u]+w[i];
48                 if(!vis[to[i]])q.push(to[i]),vis[to[i]]=1;
49             }
50     }
51 }
52 
53 il void Astar(){
54     if(dis[t]==inf) return;
55     node tmp;
56     tmp.g=0,tmp.f=dis[t],tmp.id=t;
57     Q.push(tmp);
58     while(!Q.empty()){
59         tmp=Q.top();Q.pop();
60         if(tmp.id==s) {ans[++tot]=tmp.g;if(tot>=k)return;}
61         for(int i=H[tmp.id];i;i=Net[i]){
62             node tp;
63             tp.g=tmp.g+W[i];
64             tp.f=tp.g+dis[To[i]];
65             tp.id=To[i];
66             Q.push(tp);
67         }
68     }
69 }
70 
71 int main(){
72     while(scanf("%d%d",&n,&m)==2){
73         memset(h,0,sizeof(h));cnt1=0;
74         memset(H,0,sizeof(H));cnt2=0;
75         int u,v,c;
76         For(i,1,m) u=gi(),v=gi(),c=gi(),add(u,v,c);
77         s=gi(),t=gi(),k=gi();
78         if(s==t)k++;
79         spfa();
80         Astar();
81         if(tot<k)cout<<-1;
82         else cout<<ans[k];
83     }
84     return 0;
85 }