<span>SPOJ3267 D-query（主席树模版）</span>

/* ***********************************************
Author        :devil
************************************************ */
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <cmath>
#include <stdlib.h>
using namespace std;
typedef long long LL;
const int inf=0x3f3f3f3f;
const int mod=1e9+7;
const int N=3e4+10;
const int M=N*100;
int n,q,tot,x,y;
int a[N],T[N],ls[M],rs[M],c[M];
int build(int l,int r)
{
    int node=tot++;
    c[node]=0;
    if(l!=r)
    {
        int mid=(l+r)>>1;
        ls[node]=build(l,mid);
        rs[node]=build(mid+1,r);
    }
    return node;
}
int update(int node,int pos,int val)
{
    int newnode=tot++,tmp=newnode;
    c[newnode]=c[node]+val;
    int l=1,r=n;
    while(l<r)
    {
        int mid=(l+r)>>1;
        if(pos<=mid)
        {
            ls[newnode]=tot++;
            rs[newnode]=rs[node];
            newnode=ls[newnode];
            node=ls[node];
            r=mid;
        }
        else
        {
            rs[newnode]=tot++;
            ls[newnode]=ls[node];
            newnode=rs[newnode];
            node=rs[node];
            l=mid+1;
        }
        c[newnode]=c[node]+val;
    }
    return tmp;
}
int query(int node,int pos)
{
    int ret=0,l=1,r=n;
    while(pos<r)
    {
        int mid=(l+r)>>1;
        if(pos<=mid)
        {
            r=mid;
            node=ls[node];
        }
        else
        {
            ret+=c[ls[node]];
            node=rs[node];
            l=mid+1;
        }
    }
    return ret+c[node];
}
int main()
{
    //freopen("in.txt","r",stdin);
    while(~scanf("%d",&n))
    {
        tot=0;
        for(int i=1;i<=n;i++) scanf("%d",&a[i]);
        T[n+1]=build(1,n);
        map<int,int>mp;
        for(int i=n;i>=1;i--)
        {
            if(mp.find(a[i])==mp.end()) T[i]=update(T[i+1],i,1);
            else
            {
                int tmp=update(T[i+1],mp[a[i]],-1);
                T[i]=update(tmp,i,1);
            }
            mp[a[i]]=i;
        }
        scanf("%d",&q);
        while(q--)
        {
            scanf("%d%d",&x,&y);
            printf("%d\n",query(T[x],y));
        }
    }
    return 0;
}