POJ 2449 Remmarguts' Date

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 const int maxn = 1010;
18 struct arc{
19     int to,w,next;
20     arc(int x = 0,int y = 0,int z = -1){
21         to = x;
22         w = y;
23         next = z;
24     }
25 };
26 struct node{
27     int g,h,to;
28     node(int x = 0,int y = 0,int z = 0){
29         g = x;
30         h = y;
31         to = z;
32     }
33     bool operator < (const node &x) const{
34         return x.g + x.h < g+h;
35     }
36 };
37 arc e[200010];
38 int head[maxn],tail[maxn],d[maxn],tot,n,m,s,t,kth;
39 int cnt[maxn];
40 void add(int u,int v,int w){
41     e[tot] = arc(v,w,head[u]);
42     head[u] = tot++;
43     e[tot] = arc(u,w,tail[v]);
44     tail[v] = tot++;
45 }
46 priority_queue< pii,vector< pii >,greater< pii > >q;
47 priority_queue<node>qq;
48 void dijkstra(){
49     for(int i = 1; i <= n; i++) d[i] = INF;
50     while(!q.empty()) q.pop();
51     d[t] = 0;
52     q.push(make_pair(d[t],t));
53     while(!q.empty()){
54         int u = q.top().second;
55         int w = q.top().first;
56         q.pop();
57         if(w > d[u]) continue;
58         for(int i = tail[u]; ~i; i = e[i].next){
59             if(d[e[i].to] > d[u] + e[i].w){
60                 d[e[i].to] = d[u] + e[i].w;
61                 q.push(make_pair(d[e[i].to],e[i].to));
62             }
63         }
64     }
65 }
66 int Astar(){
67     while(!qq.empty()) qq.empty();
68     memset(cnt,0,sizeof(cnt));
69     qq.push(node(0,d[s],s));
70     while(!qq.empty()){
71         node now = qq.top();
72         qq.pop();
73         if(++cnt[now.to] > kth) continue;
74         if(cnt[t] == kth) return now.g;
75         for(int i = head[now.to]; ~i; i = e[i].next)
76             qq.push(node(now.g+e[i].w,d[e[i].to],e[i].to));
77 
78     }
79     return -1;
80 }
81 int main() {
82     int u,v,w;
83     while(~scanf("%d %d",&n,&m)){
84         memset(head,-1,sizeof(head));
85         memset(tail,-1,sizeof(tail));
86         for(int i = 0; i < m; i++){
87             scanf("%d %d %d",&u,&v,&w);
88             add(u,v,w);
89         }
90         scanf("%d %d %d",&s,&t,&kth);
91         dijkstra();
92         if(s == t) ++kth;
93         printf("%d\n",Astar());
94     }
95     return 0;
96 }