[CDQ分治 并查集] BZOJ 3237 [Ahoi2013]连通图

考虑CDQ分治 把这半边对后半边没有影响的操作做了 然后分治

用并查集维护 开个栈暴力还原

#include<cstdio>
#include<cstdlib>
using namespace std;

inline char nc()
{
	static char buf[100000],*p1=buf,*p2=buf;
	if (p1==p2) { p2=(p1=buf)+fread(buf,1,100000,stdin); if (p1==p2) return EOF; }
	return *p1++;
}

inline void read(int &x)
{
	char c=nc(),b=1;
	for (;!(c>='0' && c<='9');c=nc()) if (c=='-') b=-1;
	for (x=0;c>='0' && c<='9';x=x*10+c-'0',c=nc()); x*=b;
}

const int N=200005;

struct edge{
	int u,v;
}edges[N];

struct abcd{
	int idx;
	int c,e[5];
}eve[N];

int n,m,K;
int clk,del[N];
int ans[N];

int fat[N];
int Stk[50*N],pnt;

inline int Fat(int u){
	if (fat[u]==u) return u;
	Stk[++pnt]=u; Stk[++pnt]=fat[u];
	return fat[u]=Fat(fat[u]);
}

inline void Union(int x,int y){
	int fx=Fat(x),fy=Fat(y);
	if (fx!=fy)
		Stk[++pnt]=fx,Stk[++pnt]=fat[fx],fat[fx]=fy;
}

inline void Restore(int bot){
	while (pnt!=bot)
		fat[Stk[pnt-1]]=Stk[pnt],pnt-=2;
}

inline void Solve(int l,int r){
	int bot=pnt;
	if (l==r){
		int flag=1;
		for (int i=1;i<=eve[l].c && flag;i++) 
			if (Fat(edges[eve[l].e[i]].u)!=Fat(edges[eve[l].e[i]].v))
				flag=0;
		ans[eve[l].idx]=flag;
		Restore(bot);
		return;
	}
	int mid=(l+r)>>1;
	clk++;
	for (int i=l;i<=mid;i++)
		for (int j=1;j<=eve[i].c;j++)
			del[eve[i].e[j]]=clk;
	for (int i=mid+1;i<=r;i++)
		for (int j=1;j<=eve[i].c;j++)
			if (del[eve[i].e[j]]!=clk)
				Union(edges[eve[i].e[j]].u,edges[eve[i].e[j]].v);
	Solve(l,mid);
	Restore(bot);
	clk++;
	for (int i=mid+1;i<=r;i++)
		for (int j=1;j<=eve[i].c;j++)
			del[eve[i].e[j]]=clk;
	for (int i=l;i<=mid;i++)
		for (int j=1;j<=eve[i].c;j++)
			if (del[eve[i].e[j]]!=clk)
				Union(edges[eve[i].e[j]].u,edges[eve[i].e[j]].v);
	Solve(mid+1,r);
	Restore(bot);
}

int main()
{
	freopen("t.in","r",stdin);
	freopen("t.out","w",stdout);
	read(n); read(m);
	for (int i=1;i<=n;i++) fat[i]=i;
	for (int i=1;i<=m;i++)
		read(edges[i].u),read(edges[i].v);
	read(K);
	for (int i=1;i<=K;i++)
	{
		read(eve[i].c); eve[i].idx=i;
		for (int j=1;j<=eve[i].c;j++) read(eve[i].e[j]);	
	}
	++clk;
	for (int i=1;i<=K;i++)
		for (int j=1;j<=eve[i].c;j++)
			del[eve[i].e[j]]=clk;
	for (int i=1;i<=m;i++)
		if (del[i]!=clk)
			Union(edges[i].u,edges[i].v);
	Solve(1,K);
	for (int i=1;i<=K;i++)
		ans[i]?printf("Connected\n"):printf("Disconnected\n");
	return 0;
}