BZOJ4998 星球联盟

BZOJ4998 星球联盟

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题目描述

传送门

题目分析

发现题目说白了就是让你动态维护强连通分量。决定使用lct来维护，外面套一个并查集来维护连通性，查的时候直接输出当前集合的大小就可以了。

是代码呢

#include <bits/stdc++.h>
using namespace std;
const int MAXN=2e5+7;
#define lc ch[x][0]
#define rc ch[x][1]
int q[MAXN],s[MAXN],size[MAXN],n,m,r[MAXN],st[MAXN],ch[MAXN][2],fa[MAXN],f[MAXN],Q,add[MAXN];
inline int find(int x){return fa[x]==x?fa[x]:fa[x]=find(fa[x]);}
inline bool nroot(int x){return ch[f[x]][0]==x||ch[f[x]][1]==x;}
inline void pushr(int x){swap(lc,rc);r[x]^=1;}
inline void pushup(int x){s[x]=s[lc]+s[rc]+add[x];}
inline void pushdown(int x)
{
	if(r[x]){
		if(lc) pushr(lc);
		if(rc) pushr(rc);
		r[x]=0;
	}
}
inline void rotate(int x)
{
	int y=f[x],z=f[y],kind=ch[y][1]==x,w=ch[x][!kind];
	if(nroot(y)) ch[z][ch[z][1]==y]=x;ch[x][!kind]=y;ch[y][kind]=w;
	if(w) f[w]=y;f[y]=x;f[x]=z;
	pushup(y);
}
inline void splay(int x)
{
	int y=x,z=0;
	st[++z]=y;
	while(nroot(y)) st[++z]=y=f[y];
	while(z) pushdown(st[z--]);
	while(nroot(x)){
		y=f[x];z=f[y];
		if(nroot(y)) rotate((ch[y][0]==x)^(ch[z][0]==y)?y:x);
		rotate(x);
	}
	pushup(x);
}
inline void access(int x)
{
	for(int y=0;x;y=x,x=f[y]=find(f[x]))
		splay(x),rc=y,pushup(x);
}
inline void makeroot(int x)
{
	access(x);splay(x);pushr(x);
}
inline int findroot(int x)
{
	access(x);splay(x);
	while(lc) pushdown(x),x=lc;
	splay(x);
	return x;
}
inline void split(int x,int y)
{
	makeroot(x);access(y);splay(y);
}
inline void merge(int x,int y)
{
	if(x==y) return;
	makeroot(x);
	if(findroot(y)!=x){
		f[x]=y;
		return;
	}
	makeroot(y);access(x);splay(x);
	int cnt=s[x];
	int L=0,R=0;
	q[++R]=x;
	while(L<R){
		x=q[++L];
		if(lc) q[++R]=lc;
		if(rc) q[++R]=rc;
		fa[x]=y;
		add[x]=s[x]=f[x]=lc=rc=0;
	}
	add[y]=s[y]=cnt;
	f[y]=0;
}
inline int read()
{
    int x=0,c=1;
    char ch=' ';
    while((ch<'0'||ch>'9')&&ch!='-')ch=getchar();
    while(ch=='-')c*=-1,ch=getchar();
    while(ch>='0'&&ch<='9')x=x*10+ch-'0',ch=getchar();
    return x*c;
}
int main()
{
	n=read();m=read();Q=read();
	for(int i=1;i<=n;i++){
		add[i]=s[i]=1;fa[i]=i;
	}
	for(int i=1;i<=m;i++){
		int x=read(),y=read();
		x=find(x),y=find(y);
		merge(x,y);
	}
	for(int i=1;i<=Q;i++){
		int x=read(),y=read();
		x=find(x);y=find(y);
		if(x==y){
			printf("%d\n",add[x]);
			continue;
		}
		makeroot(x);
		if(findroot(y)!=x){
			f[x]=y;
			puts("No");
			continue;
		}
		makeroot(y);access(x);splay(x);
		int cnt=s[x];
		int L=0,R=0;
		q[++R]=x;
		while(L<R){
			x=q[++L];
			if(lc) q[++R]=lc;
			if(rc) q[++R]=rc;
			fa[x]=y;
			add[x]=s[x]=f[x]=lc=rc=0;
		}
		add[y]=s[y]=cnt;f[y]=0;
		printf("%d\n",add[y]);
	}
	return 0;
}