即要求动态维护边双。出现环时将路径上的点合并即可。LCT维护。具体地,加边成环时makeroot+access+splay一套把这段路径提出来,暴力dfs修改并查集祖先,并将这部分与根断开,视为删除这些点,以后就以并查集中的祖先代替这些点。access时更新每个点的父亲。注意由于之前的删点操作,判断是否连通需要另开一个并查集而不能findroot。
#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;
#define ll long long
#define N 200010
#define lson tree[k].ch[0]
#define rson tree[k].ch[1]
#define lself tree[tree[k].fa].ch[0]
#define rself tree[tree[k].fa].ch[1]
char getc(){char c=getchar();while ((c<'A'||c>'Z')&&(c<'a'||c>'z')&&(c<''||c>'')) c=getchar();return c;}
int gcd(int n,int m){return m==?n:gcd(m,n%m);}
int read()
{
int x=,f=;char c=getchar();
while (c<''||c>'') {if (c=='-') f=-;c=getchar();}
while (c>=''&&c<='') x=(x<<)+(x<<)+(c^),c=getchar();
return x*f;
}
int n,m,q,fa[N],fa2[N],size[N];
struct data{int ch[],fa,rev;
}tree[N];
int find(int x){return fa[x]==x?x:fa[x]=find(fa[x]);}
int find2(int x){return fa2[x]==x?x:fa2[x]=find2(fa2[x]);}
void rev(int k){if (k) swap(lson,rson),tree[k].rev^=;}
void down(int k){if (tree[k].rev) rev(lson),rev(rson),tree[k].rev=;}
int whichson(int k){return rself==k;}
bool isroot(int k){return lself!=k&&rself!=k;}
void push(int k){if (!isroot(k)) push(tree[k].fa);down(k);}
void move(int k)
{
int fa=tree[k].fa,gf=tree[fa].fa,p=whichson(k);
if (!isroot(fa)) tree[gf].ch[whichson(fa)]=k;tree[k].fa=gf;
tree[fa].ch[p]=tree[k].ch[!p],tree[tree[k].ch[!p]].fa=fa;
tree[k].ch[!p]=fa,tree[fa].fa=k;
}
void splay(int k)
{
push(k);
while (!isroot(k))
{
int fa=tree[k].fa;
if (!isroot(fa))
if (whichson(fa)^whichson(k)) move(k);
else move(fa);
move(k);
}
}
void access(int k){for (int t=;k;t=k,k=tree[k].fa=find(tree[k].fa)) splay(k),tree[k].ch[]=t;}
void makeroot(int k){access(k),splay(k),rev(k);}
void link(int x,int y){makeroot(x),tree[x].fa=y,fa2[find2(x)]=find2(y);}
void dfs(int k,int x)
{
if (!k) return;
if (find(k)!=x) size[x]+=size[find(k)],fa[find(k)]=x;
dfs(lson,x),dfs(rson,x);
}
void addedge(int x,int y)
{
if (find2(x)!=find2(y)) link(x,y);
else
{
makeroot(x),access(y),splay(y);
dfs(tree[y].ch[],y);tree[y].ch[]=;
}
}
int main()
{
#ifndef ONLINE_JUDGE
freopen("bzoj4998.in","r",stdin);
freopen("bzoj4998.out","w",stdout);
const char LL[]="%I64d\n";
#else
const char LL[]="%lld\n";
#endif
n=read(),m=read(),q=read();
for (int i=;i<=n;i++) fa[i]=i,fa2[i]=i,size[i]=;
for (int i=;i<=m;i++)
{
int x=find(read()),y=find(read());
if (x!=y) addedge(x,y);
}
for (int i=;i<=q;i++)
{
int x=find(read()),y=find(read());
if (x!=y) addedge(x,y);
if (find(x)==find(y)) printf("%d\n",size[fa[x]]);
else printf("No\n");
}
return ;
}