蒟蒻求助，分块10分

code

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<iostream>

using namespace std;

const int MAXN=40005;
const int MAXM=2005;

template <class T>
void read(T &x){
    x=0;bool f=false;char c=getchar();
    while(c<'0'||'9'<c) f=c=='-',c=getchar();
    while('0'<=c&&c<='9') x=(x<<3)+(x<<1)+c-'0',c=getchar();
    x=f? (-x):x;
}

int n,m,a[MAXN],lsh[MAXN],len,block,tmp[MAXN];

int L[MAXM],R[MAXM],belong[MAXN],cnt[MAXM][MAXN],f[MAXM][MAXM];
bool vis[MAXN];

int sum(int l,int r,int x){
    if (l>r) return 0;
    return cnt[r][x]-cnt[l-1][x];
}

int query(int l,int r){
    int q=belong[l],p=belong[r],ans=0;  
    if (q==p){
        for (int i=l;i<=r;i++){
            ++tmp[a[i]];
            if ((tmp[a[i]]>tmp[ans])||(tmp[a[i]]==tmp[ans]&&a[i]<ans)) ans=a[i];
        }
        for (int i=l;i<=r;i++) tmp[a[i]]--;
        return lsh[ans];
    }
    ans=f[q+1][p-1];int ret=ans;
    tmp[ans]=sum(q+1,p-1,ans);
    vis[ans]=true;
    for (int i=l;i<=R[q];i++){
        tmp[a[i]]++;
        if (!vis[a[i]]){
            tmp[a[i]]+=sum(q+1,p-1,a[i]);
            vis[a[i]]=true;
        }
    }
    for (int i=L[p];i<=r;i++){
        tmp[a[i]]++;
        if (!vis[a[i]]){
            tmp[a[i]]+=sum(q+1,p-1,a[i]);
            vis[a[i]]=true;
        }
    }
    for (int i=l;i<=R[q];i++){
        if ((tmp[a[i]]>tmp[ans])||((tmp[a[i]]==tmp[ans])&&a[i]<ans)) ans=a[i];
    }
    for (int i=L[p];i<=r;i++){
        if ((tmp[a[i]]>tmp[ans])||((tmp[a[i]]==tmp[ans])&&a[i]<ans)) ans=a[i];
    }
    for (int i=l;i<=R[q];i++) tmp[a[i]]=0,vis[a[i]]=0;
    for (int i=L[p];i<=r;i++) tmp[a[i]]=0,vis[a[i]]=0;
    tmp[ret]=0;vis[ret]=0;
    return lsh[ans];
}

int l0,r0,last,x,y;

int main(){
    read(n);read(m);
    for (int i=1;i<=n;i++) read(a[i]),lsh[i]=a[i];  
    sort(lsh+1,lsh+1+n);
    int tot=unique(lsh+1,lsh+1+n)-lsh-1;
    for (int i=1;i<=n;i++){
        a[i]=lower_bound(lsh+1,lsh+1+tot,a[i])-lsh;
    }
    len=sqrt(n);block=n/len;
    if (len*block!=n) block++;
    for (int i=1;i<=block;i++){
        L[i]=R[i-1]+1;
        R[i]=min(i*len,n);
        for (int j=L[i];j<=R[i];j++){
            belong[j]=i;
        }
    }

    for (int i=1;i<=block;i++){
        for (int j=1;j<=n;j++) cnt[i][j]=cnt[i-1][j];
        for (int j=L[i];j<=R[i];j++)    cnt[i][a[j]]++;
    }
    for (int i=1;i<=block;i++){
        memset(tmp,0,sizeof(tmp));
        for (int j=i;j<=block;j++){
            for (int k=L[j];k<=R[j];k++){
                tmp[a[k]]++;
                if ((tmp[a[k]]>tmp[f[i][j]])||((tmp[a[k]]==tmp[f[i][j]])&&a[k]<f[i][j])) f[i][j]=a[k];
            }
        }
    }
    memset(tmp,0,sizeof(tmp));
    while(m--){
        read(l0);read(r0);
        x=((l0+last-1)%n)+1,y=((r0+last-1)%n)+1;
        if (x>y) swap(x,y);
        printf("%lld\n",last=query(x,y));
    }
}