题目
做法
单点修改主席树
纯粹按模板题的做法,建完主席树后修改一个点后面所有的树都得修改(O(mnlogn)),T飞了
树状数组套主席树,在主席树根结点上用树状数组跳着修改O(mlogn^2)
My complete code
// luogu-judger-enable-o2
#include<cstdio>
#include<algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>
#include <cctype>
using namespace std;
typedef long long LL;
const LL maxn=1e5+10;
struct node{
LL l,r,k,val,now;
}q[maxn];
LL n,m,num,num1,num2,cnt;
LL b[maxn<<1],a[maxn],lt[maxn<<7],rt[maxn<<7],date[maxn<<7],root[maxn],que1[maxn],que2[maxn];
inline LL read(){
char c; LL f=1;
c=getchar();
while(c<'0'||c>'9'){
if(c=='-')
f=-1;
c=getchar();
}
LL x=0;
while(c>='0'&&c<='9'){
x=x*10+c-'0';
c=getchar();
}
return x*f;
}
inline LL lowbit(LL x){
return x&-x;
}
inline void update(LL x,LL l,LL r,LL c,LL val){
while(true){
LL mid=(l+r)>>1;
date[x]+=val;
if(l==r)
return;
if(c<=mid){
if(!lt[x]) lt[x]=++num;
x=lt[x],r=mid;
}else{
if(!rt[x]) rt[x]=++num;
x=rt[x],l=mid+1;
}
}
}
inline void add(LL x,LL v){
LL now=std::lower_bound(b+1,b+1+cnt,a[x])-b;
for(LL i=x;i<=n;i+=lowbit(i)){
if(!root[i])
root[i]=++num;
update(root[i],1,cnt,now,v);
}
}
inline LL query(LL l,LL r,LL k){
while(l!=r){
LL sum=0,mid=(l+r)>>1;
for(LL i=1;i<=num1;++i)
sum+=date[lt[que1[i]]];
for(LL i=1;i<=num2;++i)
sum-=date[lt[que2[i]]];
if(sum>=k){
for(LL i=1;i<=num1;++i)
que1[i]=lt[que1[i]];
for(LL i=1;i<=num2;++i)
que2[i]=lt[que2[i]];
r=mid;
}else{
for(LL i=1;i<=num1;++i)
que1[i]=rt[que1[i]];
for(LL i=1;i<=num2;++i)
que2[i]=rt[que2[i]];
return query(mid+1,r,k-sum);
l=mid+1,k-=sum;
}
}
return l;
}
int main(){
n=read(),m=read();
for(LL i=1;i<=n;++i)
a[i]=b[++cnt]=read();
for(LL i=m;i>=1;--i){
char s[100];
scanf(" %s",s);
if(s[0]=='Q')
q[i].l=read(),q[i].r=read(),q[i].k=read();
else
q[i].k=0,
q[i].now=read(),q[i].val=read(),
b[++cnt]=q[i].val;
}
std::sort(b+1,b+cnt+1);
cnt=std::unique(b+1,b+1+cnt)-b-1;
for(LL i=1;i<=n;++i)
add(i,1);
while(m){
if(q[m].k){
num1=num2=0;
for(LL j=q[m].r;j;j-=lowbit(j))
que1[++num1]=root[j];
for(LL j=q[m].l-1;j;j-=lowbit(j))
que2[++num2]=root[j];
printf("%lld
",b[query( 1,cnt,q[m].k )]);
}else{
add(q[m].now,-1),
a[q[m].now]=q[m].val,
add(q[m].now,1);
}
--m;
}
return 0;
}