$Luogu$ $P1972$ $[SDOI2009]$ $HH$ 的项链

//省略头文件
using namespace std;
inline int read()
{
	int ret=0,f=1;
	char ch=getchar();
	while(ch>'9'||ch<'0')
	{
		if(ch=='-')
			f=-1;
		ch=getchar();
	}
	while(ch>='0'&&ch<='9')
	{
		ret=(ret<<1)+(ret<<3)+ch-'0';
		ch=getchar();
	}
	return ret*f;
}
int n,q,nxt=1,nl,nr,no,num,a[1000005],bit[1000005],pos[1000005],ans[1000005];
struct queries
{
    int l,r,id;
}qry[1000005];
inline bool cmp(queries x,queries y)
{
	return y.r>x.r;
}
inline void modify(int x,int y)
{
	for(;x<=n;x+=x&-x)
		bit[x]+=y;
}
inline int query(int x)
{
    int ans=0;
	for(;x;x-=x&-x)
		ans+=bit[x];
	return ans;
}
int main()
{
	n=read();
	for(register int i=1;i<=n;i++)
		a[i]=read();
	q=read();
	for(register int i=1;i<=q;i++)
	{
		qry[i].l=read();
		qry[i].r=read();
		qry[i].id=i;
	}
	sort(qry+1,qry+q+1,cmp);
	for(register int i=1;i<=q;i++)
	{
		nl=qry[i].l;
		nr=qry[i].r;
		for(register int j=nxt;j<=nr;j++)
		{
			if(pos[a[j]])
				modify(pos[a[j]],-1);
			modify(j,1);
			pos[a[j]]=j;
		}
		nxt=nr+1;
		ans[qry[i].id]=query(nr)-query(nl-1);
	}
    for(register int i=1;i<=q;i++)
		printf("%d
",ans[i]);
    return 0;
}