bzoj 2049 [SDOI2008]洞穴勘测 (LCT)

题目大意：维护一个森林，支持边的断，连，以及查询连通性

LCT裸题 洛谷P2147传送门

1A了，给自己鼓鼓掌

#include <cstdio>
#include <algorithm>
#include <cstring>
#define il inline
#define inf 500000
#define N 10100
using namespace std;

int n,m,tp;
int stk[N];
struct LinkCutTree{
    int fa[N],ch[N][2],rv[N];
    il int idf(int x){return ch[fa[x]][0]==x?0:1;}
    il void con(int x,int ff,int p){fa[x]=ff,ch[ff][p]=x;}
    il int isroot(int x){return (ch[fa[x]][0]!=x&&ch[fa[x]][1]!=x)?1:0;}
    il void rev(int x){swap(ch[x][0],ch[x][1]),rv[x]^=1;}
    il void pushdown(int x)
    {
        if(!rv[x]) return;
        if(ch[x][0]) rev(ch[x][0]);
        if(ch[x][1]) rev(ch[x][1]);
        rv[x]=0;
    }
    il void rot(int x)
    {
        int y=fa[x];int ff=fa[y];int px=idf(x);int py=idf(y);
        if(!isroot(y)) ch[ff][py]=x;
        fa[x]=ff;con(ch[x][px^1],y,px),con(y,x,px^1);
        //pushup(y),pushup(x);
    }
    void splay(int x)
    {
        int y=x;stk[++tp]=x;
        while(!isroot(y)){stk[++tp]=fa[y],y=fa[y];}
        while(tp){pushdown(stk[tp--]);}
        while(!isroot(x))
        {
            y=fa[x];
            if(isroot(y)) rot(x);
            else if(idf(y)==idf(x)) rot(y),rot(x);
            else rot(x),rot(x);
        }
    }
    void access(int x){for(int y=0;x;y=x,x=fa[x])splay(x),ch[x][1]=y;/*pushup(x)*/}
    il void mkroot(int x){access(x),splay(x),rev(x);}
    il void split(int x,int y){mkroot(x),access(y),splay(y);}
    int findrt(int x){access(x),splay(x);while(ch[x][0])pushdown(x),x=ch[x][0];return x;}
    il void link(int x,int y){mkroot(x);if(findrt(y)!=x)fa[x]=y;}
    il void cut(int x,int y){mkroot(x);if(findrt(y)==x&&fa[x]==y&&!ch[x][1])fa[x]=ch[y][0]=0;/*pushup(y)*/}
}lct;
int gint()
{
    int rett=0,fh=1;char c=getchar();
    while(c<'0'||c>'9'){if(c=='-')fh=-1;c=getchar();}
    while(c>='0'&&c<='9'){rett=(rett<<3)+(rett<<1)+c-'0';c=getchar();}
    return rett*fh;
}

int main()
{
    n=gint(),m=gint();
    int fl,x,y;char str[20];
    for(int i=1;i<=m;i++)
    {
        scanf("%s",str);
        x=gint(),y=gint();
        if(str[0]=='C'){lct.link(x,y);}
        if(str[0]=='D'){lct.cut(x,y);}
        if(str[0]=='Q'){
            if(lct.findrt(x)==lct.findrt(y))
                printf("Yes\n");
            else printf("No\n");}
    }
    return 0;
}