P2147 [SDOI2008]洞穴勘测

传送门

维护森林中点之间的连通性，有加边和删边操作，保证不出现环

显然直接 $LCT$ 维护，模板套进去就好了

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
using namespace std;
typedef long long ll;
inline int read()
{
    int x=0,f=1; char ch=getchar();
    while(ch<'0'||ch>'9') { if(ch=='-') f=-1; ch=getchar(); }
    while(ch>='0'&&ch<='9') { x=(x<<1)+(x<<3)+(ch^48); ch=getchar(); }
    return x*f;
}
const int N=1e5+7,M=1e6+7;
int c[N][2],fa[N];
bool rev[N];
inline void pushdown(int x)
{
    if(!rev[x]||!x) return;
    int &lc=c[x][0],&rc=c[x][1];
    rev[x]=0; swap(lc,rc);
    if(lc) rev[lc]^=1;
    if(rc) rev[rc]^=1;
}
inline void rever(int x) { rev[x]^=1; pushdown(x); }
inline bool notroot(int x) { return (c[fa[x]][0]==x)|(c[fa[x]][1]==x); }
inline void rotate(int x)
{
    int y=fa[x],z=fa[y],d=(c[y][1]==x);
    if(notroot(y)) c[z][c[z][1]==y]=x;
    fa[x]=z; fa[y]=x; fa[c[x][d^1]]=y;
    c[y][d]=c[x][d^1]; c[x][d^1]=y;
}
inline void push_rev(int x)
{
    if(notroot(x)) push_rev(fa[x]);
    else pushdown(x);
    pushdown(c[x][0]); pushdown(c[x][1]);
}
inline void splay(int x)
{
    push_rev(x);
    while(notroot(x))
    {
        int y=fa[x],z=fa[y];
        if(notroot(y))
        {
            if(c[y][0]==x ^ c[z][0]==y) rotate(x);
            else rotate(y);
        }
        rotate(x);
    }
}
inline void access(int x)
{
    for(int y=0;x;y=x,x=fa[x])
        splay(x),c[x][1]=y;
}
inline void makeroot(int x) { access(x); splay(x); rever(x); }
inline int findroot(int x)
{
    access(x); splay(x); pushdown(x);
    while(c[x][0]) x=c[x][0],pushdown(x);
    splay(x);
    return x;
}
inline void link(int x,int y) { makeroot(x); if(findroot(y)!=x) fa[x]=y; }
inline void cut(int x,int y)
{
    makeroot(x);
    if(findroot(y)!=x||fa[y]!=x||c[y][0]) return;
    fa[y]=c[x][1]=0;
}
int n,m;
int main()
{
    int a,b; char s[17];
    n=read(),m=read();
    while(m--)
    {
        scanf("%s",s); a=read(),b=read();
        if(s[0]=='C') { link(a,b); continue; }
        if(s[0]=='D') { cut(a,b); continue; }
        if(findroot(a)==findroot(b)) printf("Yes
");
        else printf("No
");
    }
    return 0;
}