luogu3302 [SDOI2013]森林

前置技能：Count on a tree

然后带上一个启发式合并

#include <algorithm>
#include <iostream>
#include <cstdio>
using namespace std;
int n, m, orz, uu, vv, ww, a[80005], b[80005], rnk[80005], rem, cnt, tt[15];
int hea[80005], fa[80005], siz[80005], gra[80005][19], qaq, lst;
int rot[80005], lson[9000005], rson[9000005], sum[9000005], dep[80005];
bool vis[80005];
char ss[15];
struct Edge{
	int too, nxt;
}edge[320005];
void add_edge(int fro, int too){
	edge[++cnt].nxt = hea[fro];
	edge[cnt].too = too;
	hea[fro] = cnt;
}
int insert(int pre, int l, int r, int x){
	int rt=++qaq;
	int mid=(l+r)>>1;
	lson[rt] = lson[pre]; rson[rt] = rson[pre]; sum[rt] = sum[pre] + 1;
	if(l==r)	return rt;
	if(x<=mid)	lson[rt] = insert(lson[pre], l, mid, x);
	if(mid<x)	rson[rt] = insert(rson[pre], mid+1, r, x);
	return rt;
}
void dfs(int o, int f, int r){
	fa[o] = f;
	siz[r]++;
	dep[o] = dep[f] + 1;
	vis[o] = true;
	gra[o][0] = f;
	for(int i=1; i<=16; i++)
		gra[o][i] = gra[gra[o][i-1]][i-1];
	rot[o] = insert(rot[f], 1, rem, rnk[o]);
	for(int i=hea[o]; i; i=edge[i].nxt){
		int t=edge[i].too;
		if(t!=f)	dfs(t, o, r);
	}
}
int build(int l, int r){
	int rt=++qaq;
	int mid=(l+r)>>1;
	if(l==r)	return rt;
	if(l<=mid)	lson[rt] = build(l, mid);
	if(mid<r)	rson[rt] = build(mid+1, r);
	return rt;
}
int getLca(int uu, int vv){
	if(dep[uu]<dep[vv])	swap(uu, vv);
	for(int i=16; i>=0; i--)
		if(dep[gra[uu][i]]>=dep[vv])
			uu = gra[uu][i];
	if(uu==vv)	return uu;
	for(int i=16; i>=0; i--)
		if(gra[uu][i]!=gra[vv][i]){
			uu = gra[uu][i];
			vv = gra[vv][i];
		}
	return gra[uu][0];
}
int query(int l, int r, int k){
	int tmp=0;
	tmp -= sum[lson[tt[1]]] + sum[lson[tt[2]]];
	tmp += sum[lson[tt[3]]] + sum[lson[tt[4]]];
	if(l==r)	return l;
	int mid=(l+r)>>1;
	if(k<=tmp){
		for(int i=1; i<=4; i++)
			tt[i] = lson[tt[i]];
		return query(l, mid, k);
	}
	else{
		for(int i=1; i<=4; i++)
			tt[i] = rson[tt[i]];
		return query(mid+1, r, k-tmp);
	}
}
int myfind(int x){
	return x==fa[x]?x:fa[x]=myfind(fa[x]);
}
int main(){
	cin>>n;
	cin>>n>>m>>orz;
	for(int i=1; i<=n; i++){
		scanf("%d", &a[i]);
		b[i] = a[i];
		fa[i] = i;
	}
	sort(b+1, b+1+n);
	rem = unique(b+1, b+1+n) - (b + 1);
	for(int i=1; i<=n; i++){
		int tmp=lower_bound(b+1, b+1+rem, a[i])-b;
		rnk[i] = tmp;
	}
	for(int i=1; i<=m; i++){
		scanf("%d %d", &uu, &vv);
		add_edge(uu, vv);
		add_edge(vv, uu);
	}
	rot[0] = build(1, rem);
	for(int i=1; i<=n; i++)
		if(!vis[i])
			dfs(i, 0, i), fa[i]=i;
	while(orz--){
		scanf("%s", ss);
		if(ss[0]=='Q'){
			scanf("%d %d %d", &uu, &vv, &ww);
			uu ^= lst; vv ^= lst; ww ^= lst;
			int lca=getLca(uu, vv);
			tt[1] = rot[lca]; tt[2] = rot[gra[lca][0]];
			tt[3] = rot[uu]; tt[4] = rot[vv];
			lst = b[query(1, rem, ww)];
			printf("%d\n", lst);
		}
		else{
			scanf("%d %d", &uu, &vv);
			uu ^= lst; vv ^= lst;
			int r1=myfind(uu);
			int r2=myfind(vv);
			if(siz[r1]<siz[r2])	swap(uu, vv), swap(r1, r2);
			add_edge(uu, vv);
			add_edge(vv, uu);
			dfs(vv, uu, r1);
		}
	}
	return 0;
}