[BZOJ2733][HNOI2012][启发式合并][平衡树]永无乡

题意

#include <cstdio>
#include <iostream>
#include <cstdlib>
#include <algorithm>
#define N 200010

using namespace std;

int n,m,x,y,q;
char op;
struct lef{
lef *fa,*ch[2];
int sz,r,w,g;
}p
,*rt,*u,*v,*city
;

inline void updat(lef *x){
if(!x) return; x->sz=1;
if(x->ch[0]) x->sz+=x->ch[0]->sz;
if(x->ch[1]) x->sz+=x->ch[1]->sz;
}

inline void *reborn(lef *x){
x->fa=x->ch[0]=x->ch[1]=NULL;
x->sz=1;
}

inline void rot(lef *x){
lef *y=x->fa,*z=y->fa; int lor=x==y->ch[1];
if(z) z->ch[z->ch[1]==y]=x; x->fa=z;
if(y->ch[lor]=x->ch[lor^1]) y->ch[lor]->fa=y;
(x->ch[lor^1]=y)->fa=x; updat(y); updat(x);
}

inline void InserT(lef *&x,lef *y){
if(!x){x=y;return ;}
x->sz++;
if(x->w>y->w){
InserT(x->ch[0],y);
x->ch[0]->fa=x;
if(x->r>x->ch[0]->r)
rot(x->ch[0]);
}
else{
InserT(x->ch[1],y);
x->ch[1]->fa=x;
if(x->r>x->ch[1]->r)
rot(x->ch[1]);
}
}

inline char C(){
static char buf[100000],*p1=buf,*p2=buf;
if(p1==p2){
p2=(p1=buf)+fread(buf,1,100000,stdin);
if(p1==p2) return EOF;
}
return *p1++;
}

inline void reaD(int &x){
char Ch=C();x=0;
for(;Ch>'9'||Ch<'0';Ch=C());
for(;Ch>='0'&&Ch<='9';x=x*10+Ch-'0',Ch=C());
}

inline lef *Getrt(lef *x){
if(!x) return NULL;
while(x->fa) x=x->fa;
return x;
}

void merge(lef *x,lef *y){
if(x->ch[0]) merge(x->ch[0],y);
if(x->ch[1]) merge(x->ch[1],y);
reborn(x);
InserT(y,x);
}

int check(lef *x,int y){
int k=1;
if(x->ch[0]) k+=x->ch[0]->sz;
if(k==y) return x->g;
if(k<y) return check(x->ch[1],y-k);
else return check(x->ch[0],y);
}

int main(){
freopen("2733.in","r",stdin);
freopen("2733.out","w",stdout);
reaD(n);reaD(m);
for(int i=1;i<=n;i++){
city[i]=&p[i];
reaD(city[i]->w);
city[i]->r=rand();
city[i]->g=i;
city[i]->sz=1;
}
for(int i=1;i<=m;i++){
reaD(x); reaD(y);
u=Getrt(city[x]);
v=Getrt(city[y]);
if(u==v) continue;
if(u->sz>v->sz) swap(u,v);
merge(u,v);
}
reaD(q);
for(int i=1;i<=q;i++){
while((op=C())!='Q'&&op!='B');
if(op=='B'){
reaD(x);reaD(y);
u=Getrt(city[x]);
v=Getrt(city[y]);
if(u==v) continue;
if(u->sz>v->sz) swap(u,v);
merge(u,v);
}
else{
reaD(x);reaD(y);
u=Getrt(city[x]);
if(!u||y>u->sz) puts("-1");
else printf("%d\n",check(u,y));
}
}
}