bzoj1015: [JSOI2008]星球大战starwar

题解：并查集；

发现按顺序拆集合不行，就干脆反过来来合并集合；

#include<iostream>
#include<cstring>
#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<iomanip>
#include<map>
#include<set>
#include<vector>
#include<ctime>
#include<cmath>
using namespace std;
const int maxn=404000;
struct node{
    int y,next;
}e[maxn];
int linkk[maxn],len=0,fa[maxn],vis[maxn],q[maxn],g[maxn];
int n,m,k;
void insert(int x,int y){
    e[++len].y=y;
    e[len].next=linkk[x];
    linkk[x]=len;
}
int getfather(int x){
    int y=x,temp;
    while(fa[y]!=y)y=fa[y];
    while(y!=x){
        temp=fa[x];
        fa[x]=y;
        x=temp;
    }
    return y;
}
bool Union(int x,int y){
    x=getfather(x);y=getfather(y);
    if(x==y)return 0;
    fa[x]=y;return 1;
}
void work(){
    scanf("%d %d",&n,&m);int x,y;
    for(int i=1;i<=m;i++){
        scanf("%d %d",&x,&y);x++,y++;
        insert(x,y);insert(y,x);
    }
    scanf("%d",&k);
    for(int i=1;i<=k;i++){scanf("%d",&q[i]);q[i]++;vis[q[i]]=1;}
    for(int x=1;x<=n;x++){
        fa[x]=x;
        if(vis[x])continue;
        for(int i=linkk[x];i;i=e[i].next){
            if(vis[e[i].y])continue;
            Union(x,e[i].y);
        }
    }
    int ans=0;
    for(int i=1;i<=n;i++){
        fa[i]=getfather(i);
        if(fa[i]==i&&!vis[i])ans++;
    }
    for(int j=k;j>=1;j--){
        x=q[j];vis[x]=0;
        for(int i=linkk[x];i;i=e[i].next){
            if(vis[e[i].y])continue;
            if(Union(e[i].y,x))ans--;
        }
        g[j]=ans;
    }
    for(int i=1;i<=k;i++)printf("%d
",g[i]);
}
int main(){
    work();
    return 0;
}