bzoj 2733: [HNOI2012]永无乡

23333用并查集维护联通，然后网上搞splay就行啦。

%高端splay写法（2333写在struct里了，是不是叫构造函数什么的？？）

#include<bits/stdc++.h>
#define N 100005
#define LL long long
#define ls tr[x][0]
#define rs tr[x][1]
using namespace std;
inline int ra()
{
    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 f[N],n,m,Q,v[N],q[N],l,r;char op[5];
int find(int x){return f[x]==x?x:f[x]=find(f[x]);}
struct Tsplay{
    int fa[N],tr[N][2],root,v[N],size[N];
    void update(int x) {size[x]=size[ls]+size[rs]+1;}
    bool which (int x){return tr[fa[x]][1]==x;}
    void rotate(int x)    //（这个rotate看起来很不错233）
    {
        int y=fa[x],z=fa[y]; bool nx=which(x),ny=which(y);
        tr[y][nx]=tr[x][!nx]; fa[tr[x][!nx]]=y;
        fa[y]=x; tr[x][!nx]=y; fa[x]=z;
        if (z) tr[z][ny]=x; update(y); update(x);
    }
    void splay(int x, int aim)  //（翻转到以aim为父亲节点的点）
    {
        while (fa[x]!=aim)
        {
            int y=fa[x],z=fa[y];
            if (z==aim) rotate(x);
            else if (which(x)==which(y)) rotate(y),rotate(x);
            else rotate(x),rotate(x); 
        }
        if (!aim) root=x; update(x); 
    }
    void insert(int a)
    {
        int x=root;
        for(;;)
        {
            if (v[a]<v[x])
            {
                if (!ls) return ls=a,fa[a]=x,splay(a,0),void();
                else x=ls;
            }
            else
            {
                if (!rs) return rs=a,fa[a]=x,splay(a,0),void();
                else x=rs;
            }
        }
    }
    void merge(int a, int b)
    {
        if (size[a]<size[b]) swap(a,b);
        f[b]=a,root=a;
        l=0,r=1; q[0]=b;
        while (l<r)
        {
            int x=q[l++];
            if (ls) q[r++]=ls;
            if (rs) q[r++]=rs;
            ls=rs=0; size[x]=1; insert(x);
        }
        splay(a,0);
    }
    int rank(int a, int k)
    {
        if (k>size[a]) return -1;
        int x=root;
        for(;;)
        {
            if (size[ls]>=k) x=ls;
            else if (size[ls]+1==k) return x;
            else k-=(size[ls]+1),x=rs;
        }
    }
}T;
int main()
{
    n=ra(); m=ra();
    for (int i=1; i<=n; i++) T.v[i]=ra(),f[i]=i;
    for (int i=1; i<=m; i++)
    {
        int p=find(ra()),q=find(ra());
        if (p!=q) T.splay(q,0),T.splay(p,0),T.merge(q,p);
    }
    int t=ra();
    while (t--)
    {
        int a,b;
        scanf("%s%d%d",op,&a,&b);
        if (op[0]=='B') {
            if (find(a)!=find(b)) a=find(a),b=find(b),T.splay(a,0),T.splay(b,0),T.merge(a,b);
        }
        else 
        {
            a=find(a); T.splay(a,0);
            printf("%d
",T.rank(a,b));
        }
    }
    return 0;
}