bzoj 1015 维护连通块个数，离线并查集

水。

 /**************************************************************
     Problem: 1015
     User: idy002
     Language: C++
     Result: Accepted
     Time:2072 ms
     Memory:14796 kb
 ****************************************************************/

 #include <cstdio>
 #include <vector>
 #define maxn 400010
 using namespace std;

 int fa[maxn];
 void init( int n ) {
     for( int i=; i<=n; i++ ) fa[i] = i;
 }
 int find( int a ) {
     return fa[a]==a ? a : fa[a]=find(fa[a]);
 }
 void unon( int a, int b ) {
     a = find(a);
     b = find(b);
     fa[a] = b;
 }

 int n, m;
 vector<int> g[maxn];
 bool vis[maxn];
 int ans[maxn], opt[maxn], tot, cnt;

 int main() {
     scanf( "%d%d", &n, &m );
     for( int i=,u,v; i<=m; i++ ) {
         scanf( "%d%d", &u, &v );
         u++, v++;
         g[u].push_back(v);
         g[v].push_back(u);
     }
     scanf( "%d", &tot );
     for( int i=; i<=tot; i++ ) {
         scanf( "%d", opt+i );
         opt[i]++;
         vis[opt[i]] = true;
     }

     init(n);
     for( int u=; u<=n; u++ ) {
         if( vis[u] ) continue;
         for( int t=; t<g[u].size(); t++ ) {
             int v = g[u][t];
             if( vis[v] ) continue;
             unon(u,v);
         }
     }
     cnt = ;
     for( int i=; i<=n; i++ ) if( fa[i]==i && !vis[i]) cnt++;

     for( int i=tot; i>=; i-- ) {
         ans[i] = cnt;
         cnt++;
         int u = opt[i];
         vis[u] = false;
         for( int t=; t<g[u].size(); t++ ) {
             int v = g[u][t];
             if( vis[v] ) continue;
             if( find(u)!=find(v) ) {
                 unon(u,v);
                 cnt--;
             }
         }
     }
     ans[] = cnt;
     for( int i=; i<=tot; i++ )
         printf( "%d\n", ans[i] );
 }