【BZOJ2733】永無鄉

題目鏈接：傳送門
題解：
splay啓發式合併，每次暴力拆較小的子樹插入到另一個子樹中

//by sdfzchy
#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define ls t[x].ch[0]
#define rs t[x].ch[1]
#define pa t[x].fa
using namespace std;
typedef long long LL;
const int inf=(1<<30),N=100010,mod=1e9+7;
int n,m,fa[N],val[N];
inline int in()
{
    char tmp=getchar();
    int res=0,f=1;
    while((tmp<'0'||tmp>'9')&&tmp!='-')tmp=getchar();
    if(tmp=='-') f=-1,tmp=getchar();
    while(tmp>='0'&&tmp<='9')   res=(res<<1)+(res<<3)+(tmp^48),tmp=getchar();
    return res*f;
}
inline int find(int x) {return fa[x]==x?fa[x]:fa[x]=find(fa[x]);}
struct Splay
{
    int cnt=0,root=0;
    struct node
    {
        int ch[2],fa,siz,val;
    }t[N];
    void init() {for(int i=1;i<=n;i++) t[i].val=val[i],t[i].siz=1;}
    inline int gi(int x) {return t[pa].ch[1]==x;}
    inline void upd(int x) {t[x].siz=t[ls].siz+t[rs].siz+1;}
    void rot(int x)
    {
        int f=pa,g=t[pa].fa,o=gi(x);
        if(g) t[g].ch[gi(f)]=x;pa=g;
        t[f].ch[o]=t[x].ch[!o];t[t[x].ch[!o]].fa=f;
        t[x].ch[!o]=f;t[f].fa=x;
        upd(f);upd(x);
    }
    inline void splay(int x,int tar)
    {
        for(;pa!=tar;rot(x))
            if(t[pa].fa!=tar)
                rot((gi(x)==gi(pa))?pa:x);
        if(!tar) root=x;
    }
    void ins(int p)
    {
        int x=root,f=0,v=t[p].val;
        while(x) f=x,x=(v<t[x].val?ls:rs);
        x=p;
        t[f].ch[v>t[f].val]=x;t[x].fa=f;
        splay(x,0);
    }
    void order(int x)
    {
        int l=ls,r=rs;
        ls=rs=pa=0;t[x].siz=1;
        if(l) order(l);
        ins(x);
        if(r) order(r);
    }
    void merge(int x,int y)
    {
        if(x==y) return;
        splay(x,0);splay(y,0);
        if(t[x].siz>t[y].siz) swap(x,y);
        fa[x]=y;root=y;
        order(x);
    }
    int kth(int x,int k)
    {
        splay(x,0);
        while(x)
        {
            if(k<=t[ls].siz) x=ls;
            else if(k>t[ls].siz+1) k-=t[ls].siz+1,x=rs;
            else return x;
        }
        return -1;
    }
    void print()
    {
        printf("%d\n",root);
        for(int x=1;x<=n;x++) printf("%d %d %d %d\n",ls,rs,pa,t[x].siz);
    }
}S;
char s[10];
int main()
{
//  freopen("in.in","r",stdin);
//  freopen("out.out","w",stdout);
    n=in(),m=in();
    for(int i=1;i<=n;i++) fa[i]=i,val[i]=in();
    S.init();
    for(int i=1,x,y;i<=m;i++) x=find(in()),y=find(in()),S.merge(x,y);
    m=in();
//  S.print();
    for(int i=1,x,y;i<=m;i++)
    {
        scanf("%s",s);
        if(s[0]=='B') S.merge(find(in()),find(in()));
        else x=in(),y=in(),printf("%d\n",S.kth(x,y));
//      S.print();
//      for(int i=1;i<=n;i++) cout<<fa[i]<<" ";
//      cout<<endl;
    }
    return 0;
}