【反演复习计划】【bzoj3529】数表

Orz PoPoQQQ大爷

按照他ppt的解法，这题可以划归到之前的题了OrzOrz

跪wy写的题解（Stealth Assassin）https://www.luogu.org/wiki/show?name=%E9%A2%98%E8%A7%A3+P3312

#include<bits/stdc++.h>
#define N 100005
#define fi first
#define sc second
using namespace std;
typedef long long ll;
int Q,maxn,cnt,prime[N],mu[N],d[N];
int c[10*N],ans[N],vis[N];
pair<int,int> f[N];
struct Query{int n,m,a,id;}q[N];
bool operator<(Query x,Query y){return x.a<y.a;}
inline int lowbit(int x){return (x&(-x));}
inline void add(int x,int val){
    for(int i=x;i<=maxn;i+=lowbit(i))c[i]+=val;
}
inline int query(int x){
    int ans=0;
    for(int i=x;i;i-=lowbit(i))ans+=c[i];
    return ans;
}
inline void calcmu(){
    cnt=0;memset(vis,1,sizeof(vis));mu[1]=1;
    for(int i=2;i<=maxn;i++){
        if(vis[i]){prime[++cnt]=i;mu[i]=-1;}
        for(int j=1;j<=cnt;j++){
            int t=prime[j]*i;if(t>maxn)break;
            vis[t]=0;
            if(i%prime[j]==0){mu[t]=0;break;}
            mu[t]=-mu[i];
        }
    }
    for(int i=1;i<=maxn;i++)
    for(int j=i;j<=maxn;j+=i)f[j].fi+=i;
    for(int i=1;i<=maxn;i++)f[i].sc=i;
}
inline void work(int x){
    int id=q[x].id,n=q[x].n,m=q[x].m;
    for(int i=1,j=1;i<=n;i=j+1){
        j=min(n/(n/i),m/(m/i));
        ans[id]+=(n/i)*(m/i)*(query(j)-query(i-1));
    }
}
inline int read(){
    int f=1,x=0;char ch;
    do{ch=getchar();if(ch=='-')f=-1;}while(ch<'0'||ch>'9');
    do{x=x*10+ch-'0';ch=getchar();}while(ch>='0'&&ch<='9');
    return f*x;
}
int main(){
    Q=read();
    for(int i=1;i<=Q;i++){
        q[i].n=read();q[i].m=read();q[i].a=read();q[i].id=i;
        if(q[i].n>q[i].m)swap(q[i].n,q[i].m);
        maxn=max(maxn,q[i].n);
    }
    calcmu();
    sort(q+1,q+Q+1);sort(f+1,f+maxn+1);int now=0;
    for(int i=1;i<=Q;i++){
        while(now+1<=maxn&&f[now+1].fi<=q[i].a){
            ++now;
            for(int j=f[now].sc;j<=maxn;j+=f[now].sc)
            add(j,f[now].fi*mu[j/f[now].sc]);
        }
        work(i);
    }
    for(int i=1;i<=Q;i++)printf("%d
",ans[i]&0x7fffffff);
    return 0;
}