POJ 2449 Remmarguts' Date -K短路

  1 #include <queue>
  2 #include <cstdio>
  3 #include <ctype.h>
  4 #include <cstring>
  5 #include <algorithm>
  6 
  7 using namespace std;
  8 
  9 const int MAXM=100010;
 10 const int MAXN=1010;
 11 const int INF=0x7fffffff;
 12 
 13 struct edge {
 14     int to;
 15     int next;
 16     int val;
 17     edge() {}
 18     edge(int to,int val,int next):to(to),val(val),next(next) {}
 19 };
 20 edge e[MAXM<<1],r[MAXM<<1];
 21 
 22 int head[MAXN],Head[MAXN],tot;
 23 
 24 int dis[MAXN];
 25 
 26 int n,m,S,T,k,inr;
 27 
 28 bool vis[MAXN];
 29 
 30 struct data {
 31     int to;
 32     int dist;
 33     bool operator < (data p) const {
 34         return dist+dis[to]>dis[p.to]+p.dist;
 35     }
 36 };
 37 data s;
 38 
 39 inline void read(int&x) {
 40     int f=1;register char c=getchar();
 41     for(x=0;!isdigit(c);c==‘-‘&&(f=-1),c=getchar());
 42     for(;isdigit(c);x=x*10+c-48,c=getchar());
 43     x=x*f;
 44 }
 45 
 46 inline void add(int x,int y,int v) {
 47     e[++tot]=edge(y,v,head[x]);
 48     r[tot]=edge(x,v,Head[y]);
 49     head[x]=Head[y]=tot;
 50 }
 51 
 52 inline void init() {
 53     memset(head,-1,sizeof head);
 54     memset(Head,-1,sizeof Head);
 55     tot=0;
 56 }
 57 
 58 void spfa() {
 59     queue<int> Q;
 60     for(int i=1;i<=n;++i) dis[i]=INF,vis[i]=false;
 61     Q.push(T);
 62     dis[T]=0;
 63     vis[T]=true;
 64     while(!Q.empty()) {
 65         int now=Q.front();
 66         Q.pop();
 67         vis[now]=false;
 68         for(int i=Head[now];i!=-1;i=r[i].next) {
 69             int to=r[i].to;
 70             if(dis[to]>dis[now]+r[i].val) {
 71                 dis[to]=dis[now]+r[i].val;
 72                 if(!vis[to]) vis[to]=true,Q.push(to);
 73             }
 74         }
 75     }
 76     return;
 77 }
 78 
 79 int Astar() {
 80     inr=0;
 81     if(dis[S]==-1) return -1;
 82     if(S==T) ++k;
 83     priority_queue<data> Q;
 84     s.to=S;s.dist=0;
 85     Q.push(s);
 86     while(!Q.empty()) {
 87         data now=Q.top();
 88         Q.pop();
 89         if(now.to==T) ++inr;
 90         if(inr==k) return now.dist;
 91         for(int i=head[now.to];i!=-1;i=e[i].next) {
 92             int to=e[i].to;
 93             data LC=now;
 94             LC.to=to;LC.dist=now.dist+e[i].val;
 95             Q.push(LC);
 96         }
 97     }
 98     return -1;
 99 }
100 
101 int hh() {
102     while(~scanf("%d%d",&n,&m)) {
103         init();
104         for(int x,y,z;m--;) {
105             read(x);read(y);read(z);
106             add(x,y,z);
107         }
108         read(S);read(T);read(k);
109         spfa();
110         int ans=Astar();
111         printf("%d\n",ans);
112     }
113     return 0;
114 }
115 
116 int sb=hh();
117 int main() {;}