SDOI2013 森林

#include<cstdio>
#include<algorithm>
#define N 160001
using namespace std;
int t,n,m,q,tot,edge_tot,tree_tot,cnt;
int key[N],hashh[N],deep[N],F[N],siz[N*75],siz_b[N],lc[N*75],rc[N*75],ancestor[N][26],root[N];
int front[N],nextt[N*2],to[N*2];
int read()
{
    int x=0;char c=getchar();
    while(c<‘0‘||c>‘9‘) c=getchar();
    while(c>=‘0‘&&c<=‘9‘) {x=x*10+c-‘0‘;c=getchar();}
    return x;
}
int find(int x) {return x==F[x] ? x:F[x]=find(F[x]);}
void discrete()
{
    sort(key+1,key+n+1);
    tot=unique(key+1,key+n+1)-(key+1);
}
void add(int u,int v)
{
    to[++edge_tot]=v;nextt[edge_tot]=front[u];front[u]=edge_tot;
}
void insert(int pre,int &x,int l,int r,int w)
{
    siz[x=++tree_tot]=siz[pre]+1;
    if(l==r) return;
    int mid=l+r>>1;
    if(w<=mid)
    {
        rc[x]=rc[pre];
        insert(lc[pre],lc[x],l,mid,w);
    }
    else
    {
        lc[x]=lc[pre];
        insert(rc[pre],rc[x],mid+1,r,w);
    }
}
void dfs(int now,int f)
{
    ancestor[now][0]=f;siz_b[now]=1;
    int p=lower_bound(key+1,key+tot+1,hashh[now])-key;
    insert(root[f],root[now],1,tot,p);
    for(int i=front[now];i;i=nextt[i])
    {
        if(to[i]==f) continue;
        deep[to[i]]=deep[now]+1;
        dfs(to[i],now);
        siz_b[now]+=siz_b[to[i]];
    }
}
int get_same(int x,int y)
{
    for(int i=0;i<=20;i++)
     if(y&(1<<i)) x=ancestor[x][i];
    return x;  
}
int get_lca(int x,int y)
{
    if(deep[x]<deep[y]) swap(x,y);
    x=get_same(x,deep[x]-deep[y]);
    if(x==y) return x;
    for(int i=20;i>=0;i--)
     if(ancestor[x][i]!=ancestor[y][i]) 
      {
           x=ancestor[x][i];y=ancestor[y][i];
      }
    return ancestor[x][0];
}
int query(int x,int y,int lca,int flca,int l,int r,int k)
{
    if(l==r) return l;
    int mid=l+r>>1,tmp=siz[lc[x]]+siz[lc[y]]-siz[lc[lca]]-siz[lc[flca]];
    if(k<=tmp) return query(lc[x],lc[y],lc[lca],lc[flca],l,mid,k);
    else return query(rc[x],rc[y],rc[lca],rc[flca],mid+1,r,k-tmp);
}
void unionn(int x,int y)
{
    ancestor[y][0]=x;deep[y]=deep[x]+1;
    int p=lower_bound(key+1,key+tot+1,hashh[y])-key;
    insert(root[x],root[y],1,tot,p);
    for(int i=1;i<=20;i++) ancestor[y][i]=ancestor[ancestor[y][i-1]][i-1];
    for(int i=front[y];i;i=nextt[i])
    {
        if(to[i]==x) continue;
        unionn(y,to[i]); 
    }
}
void get_ancestor()
{
    for(int i=1;i<=20;i++)
     for(int j=1;j<=n;j++)
      ancestor[j][i]=ancestor[ancestor[j][i-1]][i-1];
}
int main()
{
    //scanf("%d%d%d%d",&t,&n,&m,&q);
    t=read();n=read();m=read();q=read();    
    for(int i=1;i<=n;i++)
    {
        //scanf("%d",&key[i]);
        key[i]=read();
        F[i]=i;hashh[i]=key[i];
    }
    int x,y,z,last=0;
    char c[2];
    for(int i=1;i<=m;i++)
    {
        //scanf("%d%d",&x,&y);
        x=read();y=read();
        int r1=find(x),r2=find(y);
        F[r1]=r2;
        add(y,x);add(x,y);
    }
    discrete();
    for(int i=1;i<=n;i++) if(!ancestor[i][0]) dfs(i,0);
    get_ancestor();
    for(int i=1;i<=q;i++)
    {
        scanf("%s",c);
        if(c[0]==‘Q‘)
        {
            //scanf("%d%d%d",&x,&y,&z);
            x=read();y=read();z=read();
            x^=last;y^=last;z^=last;
            int lca=get_lca(x,y);
            last=query(root[x],root[y],root[lca],root[ancestor[lca][0]],1,tot,z);
            last=key[last];
            printf("%d\n",last);
        }
        else
        {
            //scanf("%d%d",&x,&y);
            x=read();y=read();
            x^=last;y^=last;
            int r1=find(x),r2=find(y);
            if(siz_b[r1]<siz_b[r2]) swap(r1,r2),swap(x,y);
            F[r2]=r1;siz_b[r1]+=siz_b[r2];
            add(x,y);add(y,x);
            unionn(x,y);
        }
    }
}