http://www.lydsy.com/JudgeOnline/problem.php?id=3065
思路:替罪羊树套权值线段树。
当替罪羊树某个子树大于某个比利(比例)时就暴力重构，本题时间复杂度:O(nlog^3n)
#include<algorithm>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<iostream>
#include<vector>
#define alpha 0.75
#define N 10000005
int read(){
char ch=getchar();int t=,f=;
while (ch<''||ch>''){if (ch=='-') f=-;ch=getchar();}
while (''<=ch&&ch<=''){t=t*+ch-'';ch=getchar();}
return t*f;
}
int tmp;
int n,m,sz,ans,root;
int v[],dfn[],rt[],ls[],rs[];
struct seg{int l,r,sum;}a[N];
std::vector<int>p,t,rec;
int newnode(){
if (!rec.size()) return ++sz;
else{
int k=rec.back();rec.pop_back();
return k;
}
}
void recliam(int &x){
if (!x) return;
rec.push_back(x);
recliam(a[x].l);recliam(a[x].r);
a[x].sum=;x=;
}
void insert(int &k,int l,int r,int val,int f){
if (!k) k=newnode();
if (l==r){a[k].sum+=f;return;}
int mid=(l+r)>>;
if (val<=mid) insert(a[k].l,l,mid,val,f);
else insert(a[k].r,mid+,r,val,f);
a[k].sum=a[a[k].l].sum+a[a[k].r].sum;
if (!a[k].sum) recliam(k);
}
void build(int &k,int l,int r){
int mid=(l+r)>>;
if (l>r) return;
if (l==r){
k=dfn[l];insert(rt[k],,,v[k],);return;
}
k=dfn[mid];
build(ls[k],l,mid-);build(rs[k],mid+,r);
for (int i=l;i<=r;i++)
insert(rt[k],,,v[dfn[i]],);
}
void del(int &x){
if (!x) return;recliam(rt[x]);
del(ls[x]);p.push_back(x);del(rs[x]);
x=;
}
void rebuild(int &x){
del(x);int s1=p.size();
for (int i=;i<=s1;i++) dfn[i]=p[i-];
build(x,,s1);
p.clear();
}
int modify(int k,int x,int val){
insert(rt[k],,,val,);
int t,L=a[rt[ls[k]]].sum;
if (L+==x){t=v[k];v[k]=val;}
else if (L>=x) t=modify(ls[k],x,val);
else t=modify(rs[k],x-L-,val);
insert(rt[k],,,t,-);
return t;
}
void query(int k,int l,int r){
int L=a[rt[ls[k]]].sum,R=a[rt[k]].sum;
if (l==&&r==R){t.push_back(rt[k]);return;}
if (l<=L+&&r>=L+)p.push_back(v[k]);
if (r<=L)query(ls[k],l,r);
else if (l>L+) query(rs[k],l-L-,r-L-);
else{
if (l<=L) query(ls[k],l,L);
if (R>L+) query(rs[k],,r-L-);
}
}
int solve_query(int L,int R,int K){
query(root,L,R);K--;
int l=,r=,s1=t.size(),s2=p.size();
while (l<r){
int mid=(l+r)>>,sum=;
for (int i=;i<s1;i++) sum+=a[a[t[i]].l].sum;
for (int i=;i<s2;i++)
if (p[i]>=l&&p[i]<=mid) sum++;
if (K<sum){
for (int i=;i<s1;i++) t[i]=a[t[i]].l;
r=mid;
} else{
for (int i=;i<s1;i++) t[i]=a[t[i]].r;
l=mid+;K-=sum;
}
}
t.clear();p.clear();
return l;
}
void insert(int &k,int x,int val){
if (!k){
k=++n;
insert(rt[k],,,val,);
v[k]=val;
return;
}
insert(rt[k],,,val,);
int L=a[rt[ls[k]]].sum;
if (L>=x) insert(ls[k],x,val);else insert(rs[k],x-L-,val);
if (a[rt[k]].sum*alpha>std::max((double)a[rt[ls[k]]].sum,(double)a[rt[rs[k]]].sum)){
if (tmp){
if (ls[k]==tmp) rebuild(ls[k]);
else rebuild(rs[k]);
tmp=;
}
}else tmp=k;
}
int main(){
n=read();
for (int i=;i<=n;i++) v[i]=read();
for (int i=;i<=n;i++) dfn[i]=i;
build(root,,n);
m=read();
char ch[];int x,y,K;
while (m--){
scanf("%s",ch);
x=read();y=read();x^=ans;y^=ans;
switch(ch[]){
case 'Q':K=read();K^=ans;ans=solve_query(x,y,K);printf("%d\n",ans);break;
case 'M':modify(root,x,y);break;
case 'I':tmp=;insert(root,x-,y);if (tmp){tmp=;rebuild(root);}break;
}
}
}