【BZOJ1969】[Ahoi2005]LANE 航线规划

#include <cstdio>#include <iostream>#include <cstring>#include <map>#include <utility>#define MP(A,B)	make_pair(A,B)#define lson x<<1#define rson x<<1|1using namespace std;const int maxm=200010;const int maxn=30010;typedef pair<int,int> pii;int n,m,q,cnt;int to[maxm],next[maxm],head[maxn],val[maxm],dep[maxn],fa[maxn],top[maxn],son[maxn],siz[maxn],p[maxn];int s[maxn<<2],tag[maxn<<2],qa[maxm],qb[maxm],op[maxm],ans[maxm],pa[maxm],pb[maxm];map<pii,int> mp;int rd(){	int ret=0,f=1;	char gc=getchar();	while(gc<‘0‘||gc>‘9‘)	{if(gc==‘-‘)f=-f;	gc=getchar();}	while(gc>=‘0‘&&gc<=‘9‘)	ret=ret*10+gc-‘0‘,gc=getchar();	return ret*f;}void build(int l,int r,int x){	if(l==r)	{		s[x]=(l!=1);		return ;	}	int mid=l+r>>1;	build(l,mid,lson),build(mid+1,r,rson);	s[x]=s[lson]+s[rson];}void pushdown(int x){	if(tag[x])	tag[lson]=tag[rson]=1,s[lson]=s[rson]=0,tag[x]=0;}void updata(int l,int r,int x,int a,int b){	if(a<=l&&r<=b)	{		s[x]=0,tag[x]=1;		return ;	}	pushdown(x);	int mid=l+r>>1;	if(a<=mid)	updata(l,mid,lson,a,b);	if(b>mid)	updata(mid+1,r,rson,a,b);	s[x]=s[lson]+s[rson];}int query(int l,int r,int x,int a,int b){	if(a<=l&&r<=b)	return s[x];	pushdown(x);	int mid=l+r>>1;	if(b<=mid)	return query(l,mid,lson,a,b);	if(a>mid)	return query(mid+1,r,rson,a,b);	return query(l,mid,lson,a,b)+query(mid+1,r,rson,a,b);}void add(int a,int b){	mp[MP(max(a,b),min(a,b))]=cnt,to[cnt]=b,next[cnt]=head[a],head[a]=cnt++;	to[cnt]=a,next[cnt]=head[b],head[b]=cnt++;}void dfs1(int x){	siz[x]=1;	for(int i=head[x];i!=-1;i=next[i])	{		if(!dep[to[i]]&&!val[i])		{			dep[to[i]]=dep[x]+1,fa[to[i]]=x,dfs1(to[i]),siz[x]+=siz[to[i]];			if(siz[to[i]]>siz[son[x]])	son[x]=to[i];		}		else		{			if(to[i]!=fa[x]&&!val[i]&&!val[i^1])	pa[++pa[0]]=x,pb[pa[0]]=to[i];			val[i]=1;		}	}}void dfs2(int x,int tp){	top[x]=tp,p[x]=++p[0];	if(son[x])	dfs2(son[x],tp);	for(int i=head[x];i!=-1;i=next[i])		if(!val[i]&&to[i]!=son[x])			dfs2(to[i],to[i]);}void modify(int x,int y){	while(top[x]!=top[y])	{		if(dep[top[x]]<dep[top[y]])	swap(x,y);		updata(1,n,1,p[top[x]],p[x]),x=fa[top[x]];	}	if(x==y)	return ;	if(dep[x]>dep[y])	swap(x,y);	updata(1,n,1,p[x]+1,p[y]);}int ask(int x,int y){	int ret=0;	while(top[x]!=top[y])	{		if(dep[top[x]]<dep[top[y]])	swap(x,y);		ret+=query(1,n,1,p[top[x]],p[x]),x=fa[top[x]];	}	if(x==y)	return ret;	if(dep[x]>dep[y])	swap(x,y);	return ret+query(1,n,1,p[x]+1,p[y]);}int main(){	n=rd(),m=rd();	int i,a,b;	memset(head,-1,sizeof(head));	for(i=1;i<=m;i++)	a=rd(),b=rd(),add(a,b);	while(1)	{		op[++q]=rd();		if(op[q]==-1)	break;		qa[q]=rd(),qb[q]=rd();		if(!op[q])		{			a=mp[MP(max(qa[q],qb[q]),min(qa[q],qb[q]))];			val[a]=val[a^1]=1;		}	}	dep[1]=1,dfs1(1),dfs2(1,1),build(1,n,1);	for(i=1;i<=pa[0];i++)	modify(pa[i],pb[i]);	for(i=q-1;i>=1;i--)	{		if(!op[i])	modify(qa[i],qb[i]);		else	ans[i]=ask(qa[i],qb[i]);	}	for(i=1;i<q;i++)	if(op[i])	printf("%d\n",ans[i]);	return 0;}//5 5 1 2 1 3 3 4 4 5 4 2 1 1 5 0 4 2 1 5 1 -1