POJ 2607 Fire Station

 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 INF 0x3f3f3f3f
15 #define pii pair<int,int>
16 using namespace std;
17 const int maxn = 2050;
18 struct arc{
19     int to,cost,next;
20     arc(int x = 0,int y = 0,int z = -1){
21         to = x;
22         cost = y;
23         next = z;
24     }
25 };
26 arc e[maxn*maxn];
27 int head[maxn],d[maxn],dd[maxn];
28 int tot,n,m;
29 bool done[maxn];
30 void add(int u,int v,int w){
31     e[tot] = arc(v,w,head[u]);
32     head[u] = tot++;
33     e[tot] = arc(u,w,head[v]);
34     head[v] = tot++;
35 }
36 void dijkstra(int s,int *d){
37     for(int i = 1; i <= n; ++i) done[i] = false;
38     d[s] = 0;
39     priority_queue< pii,vector< pii >,greater< pii > >q;
40     q.push(make_pair(d[s],s));
41     while(!q.empty()){
42         int u = q.top().second;
43         q.pop();
44         if(done[u]) continue;
45         done[u] = true;
46         for(int i = head[u]; ~i; i = e[i].next){
47             if(d[e[i].to] > d[u] + e[i].cost){
48                 d[e[i].to] = d[u] + e[i].cost;
49                 q.push(make_pair(d[e[i].to],e[i].to));
50             }
51         }
52     }
53 }
54 int main(){
55     while(~scanf("%d %d",&m,&n)){
56         int fire[maxn],tmp,u,v,w;
57         bool isfire[maxn] = {false};
58         memset(head,-1,sizeof(head));
59         for(int i = tot = 0; i < m; ++i){
60             scanf("%d",&tmp);
61             fire[i] = tmp;
62             isfire[tmp] = true;
63         }
64         while(~scanf("%d %d %d",&u,&v,&w)) add(u,v,w);
65         for(int i = 0; i <= n; ++i) d[i] = INF;
66         for(int i = 0; i < m; ++i) dijkstra(fire[i],d);
67         int maxv = INF,index = 1;
68         for(int i = 1; i <= n; ++i){
69             if(isfire[i]) continue;
70             memcpy(dd,d,sizeof(d));
71             dijkstra(i,dd);
72             int mmxx = 0;
73             for(int k = 1; k <= n; ++k)
74                 mmxx = max(mmxx,dd[k]);
75             if(mmxx < maxv){
76                 index = i;
77                 maxv = mmxx;
78             }
79         }
80         printf("%d\n",index);
81     }
82     return 0;
83 }