莫队TLE 萌新求问有何好的卡常方法

// luogu-judger-enable-o2
#include<bits/stdc++.h>
using namespace std;
struct query
{
    int l,r,id,block;
}q[500005];
bool cmp(query x,query y) 
{
     return (x.block)^(y.block)?x.l<y.l:((x.block%2)?x.r<y.r:x.r>y.r);
}
int tong[1000005],ans[500005],a[500005],l[500005],r[500005];
int read()
{
    int x=0; char ch=getchar();
    while(ch<'0' || ch>'9') ch=getchar();
    while(ch<='9' && ch>='0') x=x*10+ch-'0',ch=getchar();
    return x;
}
void print(int x)
{
    if(x<10) putchar(x+'0');
    else
    {
        print(x/10);
        putchar(x%10+'0');
    }
}
int main()
{
    int n,m;
    n=read();
    for(int i=1;i<=n;++i)
        a[i]=read();
    m=read();
    for(int i=1;i<=m;++i)
        q[i].l=read(),q[i].r=read(),q[i].id=i;	
    int t=sqrt(m),b=sqrt(m);//方便改代码
    for(int i=1;i<=t;++i)
        l[i]=r[i-1]+1,r[i]=i*b;
    if(r[t]<m) ++t,l[t]=r[t-1]+1,r[t]=m;
    for(int i=1;i<=t;++i)
        for(int j=l[i];j<=r[i];++j)
            q[j].block=i;
    sort(q+1,q+m+1,cmp);
    int L=q[1].l,R=q[1].r;
    for(int i=L;i<=R;++i)
    {
        ++tong[a[i]];
        if(tong[a[i]]==1) ++ans[q[1].id];
    }
    for(int i=2;i<=m;++i)
    {
        int sum=ans[q[i-1].id];
        while(L<q[i].l)
        {
            --tong[a[L]];
            if(tong[a[L]]==0) --sum;
            ++L;
        }
        while(q[i].l<L)
        {
            --L;
            ++tong[a[L]];
            if(tong[a[L]]==1) ++sum;
        }
        while(q[i].r<R)
        {
            --tong[a[R]];
            if(tong[a[R]]==0) --sum;
            --R;
        }
        while(q[i].r>R)
        {
            ++R;
            ++tong[a[R]];
            if(tong[a[R]]==1) ++sum;
        }
        ans[q[i].id]=sum;
    }
    for(int i=1;i<=m;++i)
        print(ans[i]),putchar('\n');
    return 0;
}