BZOJ 4358 坑 莫队+线段树 死T

//By SiriusRen
#include <cmath>
#include <cstdio>
#include <algorithm>
using namespace std;
#define Max(x,y) x>y?x:y;
const int N=50050,T=50050*8;
int n,m,Block,a
,block
,lmax[T],rmax[T],maxx[T],Pos[T],len[T],ans
;
struct Ask{int l,r,id;}ask
;
bool cmp(Ask a,Ask b){
if(block[a.l]==block[b.l])return a.r<b.r;
return a.l<b.l;
}
bool cmpid(Ask a,Ask b){return a.id<b.id;}
void build(int l,int r,int pos){
len[pos]=r-l+1;
if(l==r){Pos[l]=pos;return;}
int mid=(l+r)>>1,lson=pos<<1,rson=pos<<1|1;
build(l,mid,lson),build(mid+1,r,rson);
}
void insert(int pos){
maxx[pos]=lmax[pos]=rmax[pos]=!maxx[pos];
while(pos!=1){
pos>>=1;int lson=pos<<1,rson=pos<<1|1;
lmax[pos]=lmax[lson]+(lmax[lson]==len[lson])*lmax[rson];
rmax[pos]=rmax[rson]+(rmax[rson]==len[rson])*rmax[lson];
maxx[pos]=Max(maxx[lson],maxx[rson]);
maxx[pos]=Max(lmax[rson]+rmax[lson],maxx[pos]);
}
}
inline int read(){
char p=getchar();int x=0;
while(p<'0'||p>'9')p=getchar();
while(p>='0'&&p<='9')x=x*10+p-'0',p=getchar();
return x;
}
int main(){
n=read(),m=read(),build(1,n,1);
for(int i=1;i<=n;i++)a[i]=read();
for(int i=1;i<=m;i++)ask[i].l=read(),ask[i].r=read(),ask[i].id=i;
Block=sqrt(n);
for(int i=1;i<=n;i++)block[i]=(i-1)/Block+1;
sort(ask+1,ask+1+m,cmp);
for(int i=1,l=1,r=0;i<=m;i++){
for(;l<ask[i].l;l++)insert(Pos[a[l]]);
for(;l>ask[i].l;l--)insert(Pos[a[l-1]]);
for(;r<ask[i].r;r++)insert(Pos[a[r+1]]);
for(;r>ask[i].r;r--)insert(Pos[a[r]]);
ans[ask[i].id]=maxx[1];
}
for(int i=1;i<=m;i++)printf("%d\n",ans[i]);
}