P2147 [SDOI2008]洞穴勘测（LCT）

P2147 [SDOI2008]洞穴勘测

裸的LCT。

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
inline void Swap(int &a,int &b){a^=b^=a^=b;}
void read(int &x){
    char c=getchar();x=0;
    while(c<'0'||c>'9') c=getchar();
    while('0'<=c&&c<='9') x=x*10+(c^48),c=getchar();
}
#define N 10005
int n,m,ch[N][2],fa[N],rev[N];
#define lc ch[x][0]
#define rc ch[x][1]
inline bool nrt(int x){return ch[fa[x]][0]==x||ch[fa[x]][1]==x;}
inline void Rev(int x){Swap(lc,rc),rev[x]^=1;}
void down(int x){if(rev[x])Rev(lc),Rev(rc),rev[x]=0;}
void Pre(int x){if(nrt(x))Pre(fa[x]); down(x);}
void turn(int x){
    int y=fa[x],z=fa[y],l=(ch[y][1]==x),r=l^1;
    if(nrt(y)) ch[z][ch[z][1]==y]=x;
    fa[ch[x][r]]=y; fa[y]=x; fa[x]=z;
    ch[y][l]=ch[x][r]; ch[x][r]=y;
}
void splay(int x){
    Pre(x);
    for(;nrt(x);turn(x)){
        int y=fa[x],z=fa[y];
        if(nrt(y)) turn(((ch[z][1]==y)^(ch[y][1]==x))?x:y);
    }
}
void access(int x){for(int y=0;x;y=x,x=fa[x])splay(x),rc=y;}
inline void makert(int x){access(x),splay(x),Rev(x);}
int findrt(int x){
    access(x);splay(x);down(x);
    while(lc) x=lc,down(x);
    splay(x); return x;
}
void link(int x,int y){makert(x); if(findrt(y)!=x) fa[x]=y;}
void cut(int x,int y){
    makert(x);
    if(findrt(y)==x&&fa[y]==x&&!ch[y][0]) fa[y]=rc=0;
}
int main(){
    read(n);read(m); int q1,q2; char opt[12];
    while(m--){
        scanf("%s",opt); read(q1); read(q2);
        if(opt[0]=='Q') makert(q2),puts(findrt(q1)==q2?"Yes":"No");
        else if(opt[0]=='C') link(q1,q2);
        else if(opt[0]=='D') cut(q1,q2);
    }return 0;
}