d-query spoj

​​http://www.elijahqi.win/2017/07/05/d-query-spoj/​​​
Given a sequence of n numbers a1, a2, …, an and a number of d-queries. A d-query is a pair (i, j) (1 ≤ i ≤ j ≤ n). For each d-query (i, j), you have to return the number of distinct elements in the subsequence ai, ai+1, …, aj.

Input
Line 1: n (1 ≤ n ≤ 30000).
Line 2: n numbers a1, a2, …, an (1 ≤ ai ≤ 106).
Line 3: q (1 ≤ q ≤ 200000), the number of d-queries.
In the next q lines, each line contains 2 numbers i, j representing a d-query (1 ≤ i ≤ j ≤ n).
Output
For each d-query (i, j), print the number of distinct elements in the subsequence ai, ai+1, …, aj in a single line.
Example
Input
5
1 1 2 1 3
3
1 5
2 4
3 5

Output
3
2
3

#include<cstdio>
#include<algorithm>
#include<cmath>
#define N 220000
#define N1 33000
#define N2 1100000
using namespace std;
struct node{
    int l,r,id;
}data[N];
int a[N1],n1,aa[N2],m,n,ans[N];
bool cmp(node a,node b){
    if ((a.l)/n1==(b.l)/n1) return a.r<b.r;
    return ((a.l)/n1<(b.l)/n1);
}
inline int read(){
    int x=0;char ch=getchar();
    while (ch<'0'||ch>'9') ch=getchar();
    while (ch>='0'&&ch<='9') {
        x=x*10+ch-'0';ch=getchar();
    }
    return x;
}
int main(){
    //freopen("dquery.in","r",stdin);
    //freopen("dquery.out","w",stdout);
    n=read();
    for (int i=1;i<=n;++i) a[i]=read();
    m=read();
    for (int i=1;i<=m;++i) data[i].l=read(),data[i].r=read(),data[i].id=i;
    n1=sqrt(n);
    sort(data+1,data+m+1,cmp);  
    //for (int i=1;i<=m;++i) printf("%d %d\n",data[i].l,data[i].r);
    int cl=data[1].l,cr=data[1].r;
    int tmp=0;
    for (int i=data[1].l;i<=data[1].r;++i) if (++aa[a[i]]==1) tmp++;
    ans[data[1].id]=tmp;
    for (int i=2;i<=m;++i){
        int l=data[i].l,r=data[i].r,id=data[i].id;
        while (cl<l) if (--aa[a[cl++]]==0) tmp--;
        while (cl>l) if (++aa[a[--cl]]==1) tmp++;
        while (cr>r) if (--aa[a[cr--]]==0) tmp--;
        while (cr<r) if (++aa[a[++cr]]==1) tmp++;
        ans[id]=tmp;
    }
    for (int i=1;i<=m;++i) printf("%d\n",ans[i]);
    return 0;
}