CSU 2005 Nearest Maintenance Point（最短路+bitset）

  1 #include<iostream>
  2 #include<algorithm>
  3 #include<cstdio>
  4 #include<cstring>
  5 #include<queue>
  6 #include<bitset>
  7 #include<set>
  8 using namespace std;
  9 const int INF = 0x3f3f3f3f;
 10 const int maxn = 10000+5;
 11 
 12 int n,m,s,q,tot;
 13 int head[maxn],d[maxn],a[1005];
 14 bool done[maxn],flag[maxn];
 15 bitset<1005> ans[maxn];
 16 int tmp[1005];
 17 
 18 struct node
 19 {
 20     int v,w,next;
 21 }e[10*maxn];
 22 
 23 void addEdge(int u, int v, int w)
 24 {
 25     e[tot].v = v;
 26     e[tot].w = w;
 27     e[tot].next = head[u];
 28     head[u] = tot++;
 29 }
 30 
 31 struct HeapNode
 32 {
 33     int u,d;
 34     HeapNode(int u, int d):u(u),d(d){}
 35     bool operator< (const HeapNode& rhs) const
 36     {
 37         return d > rhs.d;
 38     }
 39 };
 40 
 41 
 42 void dijkstra(int st)
 43 {
 44     priority_queue<HeapNode> Q;
 45     for(int i=0;i<=n;i++)  d[i] = INF;
 46     d[st] = 0;
 47     memset(done,0,sizeof(done));
 48     Q.push(HeapNode(st,0));
 49     while(!Q.empty())
 50     {
 51         HeapNode x = Q.top(); Q.pop();
 52         int u = x.u;
 53         if(done[u])  continue;
 54         done[u] = true;
 55         for(int i=head[u];i!=-1;i=e[i].next)
 56         {
 57             int v = e[i].v;
 58             if(d[v] > d[u]+e[i].w)
 59             {
 60                 d[v] = d[u] + e[i].w;
 61                 if(!flag[v]) ans[v] = ans[u]; //如果不是特殊点，就更新
 62                 Q.push(HeapNode(v,d[v]));
 63             }
 64             else if(d[v] == d[u]+e[i].w)  ans[v]|=ans[u];  //相等的话，就加上当前点的答案
 65         }
 66     }
 67 }
 68 
 69 int main()
 70 {
 71     //freopen("in.txt","r",stdin);
 72     while(~scanf("%d%d%d%d",&n,&m,&s,&q))
 73     {
 74         tot = 0;
 75         memset(head,-1,sizeof(head));
 76         memset(flag,0,sizeof(flag));
 77         for(int i=0;i<=n;i++)  ans[i].reset();
 78         for(int i=1;i<=m;i++)
 79         {
 80             int u,v,w;
 81             scanf("%d%d%d",&u,&v,&w);
 82             addEdge(u,v,w);
 83             addEdge(v,u,w);
 84         }
 85         for(int i=1;i<=s;i++)
 86         {
 87             scanf("%d",&a[i]);
 88             addEdge(0,a[i],0);
 89             flag[a[i]] = true;
 90             ans[a[i]].set(i);  //特殊点的答案就是自己
 91         }
 92         dijkstra(0);
 93         while(q--)
 94         {
 95             int tot = 0;
 96             int x;scanf("%d",&x);
 97             for(int i=1;i<=s;i++)
 98                 if(ans[x].test(i))  tmp[tot++]=a[i];
 99             sort(tmp,tmp+tot);
100             for(int i=0;i<tot;i++)
101                 printf("%d%c",tmp[i],i==tot-1?‘\n‘:‘ ‘);
102         }
103     }
104     return 0;
105 }