bzoj2049 [Sdoi2008]Cave 洞穴勘测（lct）

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
#define ll long long
#define inf 0x3f3f3f3f
#define N 10010
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*10+ch-'0',ch=getchar();
return x*f;
}
int n,m,fa
,c
[2],q
;bool rev
;
inline bool isroot(int x){
return x!=c[fa[x]][0]&&x!=c[fa[x]][1];
}
inline void pushdown(int p){
if(!rev[p]) return;rev[p]=0;
int l=c[p][0],r=c[p][1];
rev[l]^=1;swap(c[l][0],c[l][1]);
rev[r]^=1;swap(c[r][0],c[r][1]);
}
inline void rotate(int x){
int y=fa[x],z=fa[y],l=x==c[y][1],r=l^1;
if(!isroot(y)) c[z][y==c[z][1]]=x;
fa[c[x][r]]=y;fa[y]=x;fa[x]=z;
c[y][l]=c[x][r];c[x][r]=y;
}
inline void splay(int x){
int top=0;q[++top]=x;
for(int xx=x;!isroot(xx);xx=fa[xx]) q[++top]=fa[xx];
while(top) pushdown(q[top--]);
while(!isroot(x)){
int y=fa[x],z=fa[y];
if(!isroot(y)){
if(x==c[y][1]^y==c[z][1]) rotate(x);
rotate(y);
}rotate(x);
}
}
inline void access(int x){
int y=0;
while(x){
splay(x);c[x][1]=y;y=x;x=fa[x];
}
}
inline void makeroot(int x){
access(x);splay(x);rev[x]=1;swap(c[x][0],c[x][1]);
}
inline void link(int x,int y){
makeroot(x);fa[x]=y;
}
inline void cut(int x,int y){
makeroot(x);access(y);splay(y);
c[y][0]=fa[x]=0;
}
inline int find(int x){
access(x);splay(x);while(c[x][0]) x=c[x][0];return x;
}
inline void query(int x,int y){
if(find(x)==find(y)) puts("Yes");
else puts("No");
}
int main(){
//  freopen("a.in","r",stdin);
n=read();m=read();
while(m--){
char op[10];scanf("%s",op+1);
int x=read(),y=read();
if(op[1]=='C') link(x,y);
else if(op[1]=='D') cut(x,y);
else query(x,y);
}return 0;
}