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=0; 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=1,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=1; i<=tot; i++ ) {
        scanf( "%d", opt+i );
        opt[i]++;
        vis[opt[i]] = true;
    }
 
    init(n);
    for( int u=1; u<=n; u++ ) {
        if( vis[u] ) continue;
        for( int t=0; t<g[u].size(); t++ ) {
            int v = g[u][t];
            if( vis[v] ) continue;
            unon(u,v);
        }
    }
    cnt = 0;
    for( int i=1; i<=n; i++ ) if( fa[i]==i && !vis[i]) cnt++;
 
    for( int i=tot; i>=1; i-- ) {
        ans[i] = cnt;
        cnt++;
        int u = opt[i];
        vis[u] = false;
        for( int t=0; t<g[u].size(); t++ ) {
            int v = g[u][t];
            if( vis[v] ) continue;
            if( find(u)!=find(v) ) {
                unon(u,v);
                cnt--;
            }
        }
    }
    ans[0] = cnt;
    for( int i=0; i<=tot; i++ )
        printf( "%d
", ans[i] );
}