洛谷P1972 [SDOI2009]HH的项链

莫队模版题

#include<iostream>
#include<cstdio>
#include<queue>
#include<algorithm>
#include<cmath>
#include<ctime>
#include<set>
#include<map>
#include<stack>
#include<cstring>
#pragma GCC optimize(2)
#define inf 2147483647
#define ls rt<<1
#define rs rt<<1|1
#define lson ls,nl,mid,l,r
#define rson rs,mid+1,nr,l,r
#define N 1000010
#define For(i,a,b) for(register int i=a;i<=b;i++)
#define p(a) putchar(a)
#define g() getchar()

using namespace std;

int a[N],cnt[N],b[N],l,r,ql,qr;
int n,m,size,num,now,ans[N];
struct query{
    int l,r,id;
}q[N];

inline bool cmp(query x,query y){
    return (b[x.l]^b[y.l])?b[x.l]<b[y.l]:(b[x.l]&1)?x.r<y.r:x.r>y.r;
}

void in(int &x){
    int y=1;
    char c=g();x=0;
    while(c<'0'||c>'9'){
        if(c=='-')y=-1;
        c=g();
    }
    while(c<='9'&&c>='0'){
        x=(x<<1)+(x<<3)+c-'0';c=g();
    }
    x*=y;
}
void o(int x){
    if(x<0){
        p('-');
        x=-x;
    }
    if(x>9)o(x/10);
    p(x%10+'0');
}
int main(){
    in(n);
    size=sqrt(n);
    num=ceil((double)n/size);
    For(i,1,num)
        For(j,(i-1)*size+1,i*size)
            b[j]=i;
    For(i,1,n)
        in(a[i]);
    in(m);
    For(i,1,m){
        in(q[i].l);in(q[i].r);
        q[i].id=i;
    }
    sort(q+1,q+m+1,cmp);
    l=1;r=0;
    For(i,1,m){
        ql=q[i].l;qr=q[i].r;
        while(l<ql) now-=!--cnt[a[l++]];
        while(l>ql) now+=!cnt[a[--l]]++;
        while(r<qr) now+=!cnt[a[++r]]++;
        while(r>qr) now-=!--cnt[a[r--]];
        ans[q[i].id]=now;
    }
    For(i,1,m)
        o(ans[i]),p('
');
    return 0;
}