【BZOJ3123】森林（主席树，启发式合并）

题面

题解

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<set>
#include<map>
#include<vector>
#include<queue>
using namespace std;
#define MAX 81000
#define rg register
inline int read()
{
rg int x=0,t=1;char ch=getchar();
while((ch<'0'||ch>'9')&&ch!='-')ch=getchar();
if(ch=='-')t=-1,ch=getchar();
while(ch<='9'&&ch>='0')x=x*10+ch-48,ch=getchar();
return x*t;
}
struct Line
{
int v,next;
}e[MAX<<1];
int h[MAX],cnt=1;
int p[MAX][20];
inline void Add(int u,int v)
{
e[cnt]=(Line){v,h[u]};
h[u]=cnt++;
}
struct Node
{
int ls,rs;
int v;
}t[MAX<<9];
int tot,n,T,m;
int fa[MAX],dep[MAX],rt[MAX],sum,S[MAX];
int a[MAX];
void Modify(int &now,int ff,int l,int r,int pos)
{
now=++tot;
t[now]=t[ff];
t[now].v++;
if(l==r)return;
int mid=(l+r)>>1;
if(pos<=mid)Modify(t[now].ls,t[ff].ls,l,mid,pos);
else Modify(t[now].rs,t[ff].rs,mid+1,r,pos);
}
void Build(int &now,int l,int r)
{
now=++tot;
if(l==r)return;
rg int mid=(l+r)>>1;
Build(t[now].ls,l,mid);
Build(t[now].rs,mid+1,r);
}
void dfs(int u,int ff)
{
fa[u]=p[u][0]=ff;dep[u]=dep[ff]+1;
Modify(rt[u],rt[ff],1,sum,a[u]);
for(int i=1;i<18;++i)p[u][i]=p[p[u][i-1]][i-1];
for(int i=h[u];i;i=e[i].next)
{
int v=e[i].v;
if(v==ff)continue;
dfs(v,u);
}
}
int Query(int A,int B,int C,int D,int l,int r,int k)
{
if(l==r)return l;
rg int tmp=t[t[A].ls].v+t[t[B].ls].v-t[t[C].ls].v-t[t[D].ls].v;
rg int mid=(l+r)>>1;
if(k<=tmp)return Query(t[A].ls,t[B].ls,t[C].ls,t[D].ls,l,mid,k);
else return Query(t[A].rs,t[B].rs,t[C].rs,t[D].rs,mid+1,r,k-tmp);
}
int f[MAX],size[MAX];
int getf(int x){return x==f[x]?x:f[x]=getf(f[x]);}
void merge(int x,int y){x=getf(x);y=getf(y);f[y]=x;size[x]+=size[y];size[y]=0;}
inline int LCA(int x,int y)
{
if(dep[x]<dep[y])swap(x,y);
for(int i=17;i>=0;--i)
if(dep[p[x][i]]>=dep[y])x=p[x][i];
if(x==y)return x;
for(int i=17;i>=0;--i)
if(p[x][i]!=p[y][i])
x=p[x][i],y=p[y][i];
return p[x][0];
}
int main()
{
read();
n=read();m=read();T=read();
for(rg int i=1;i<=n;++i)S[++sum]=a[i]=read(),size[i]=1;
sort(&S[1],&S[sum+1]);
sum=unique(&S[1],&S[sum+1])-S-1;
for(rg int i=1;i<=n;++i)a[i]=lower_bound(&S[1],&S[sum+1],a[i])-S;
Build(rt[0],1,sum);
for(rg int i=1;i<=m;++i)
{
rg int x=read(),y=read();
Add(x,y);Add(y,x);
if(size[getf(x)]>size[getf(y)])merge(x,y);
else merge(y,x);
}
for(rg int i=1;i<=n;++i)
{
if(!rt[i])
dfs(i,0);
}
rg char ch[20];
rg int ls=0;
while(T--)
{
scanf("%s",ch);
if(ch[0]=='Q')
{
rg int u=read()^ls,v=read()^ls,k=read()^ls;
rg int lca=LCA(u,v);
printf("%d\n",ls=S[Query(rt[u],rt[v],rt[lca],rt[p[lca][0]],1,sum,k)]);
}
else
{
rg int x=read()^ls,y=read()^ls;
if(size[getf(x)]>size[getf(y)])swap(x,y);
merge(y,x);
dfs(x,y);
Add(x,y);Add(y,x);
}
}
return 0;
}