【bzoj3994】[SDOI2015]约数个数和

题意：略

然后线性筛预处理，分块搞定

#include 
#define gc getchar()
#define N 100009
#define ll long long
using namespace std;
int T,n,m,pri[N],pd[N],cnt,mu[N],Min[N];
ll ans,d[N];
int read()
{
	int x=1;
	char ch;
	while (ch=gc,ch<'0'||ch>'9') if (ch=='-') x=-1;
	int s=ch-48;
	while (ch=gc,ch>='0'&&ch<='9') s=s*10+ch-48;
	return s*x;
}
int main()
{
	pd[d[1]=mu[1]=1]=1;
	for (int i=2;im) swap(n,m);
		for (int i=1,j;i<=n;i=j+1)
		{
			j=min(n/(n/i),m/(m/i));
			ans+=(ll)(mu[j]-mu[i-1])*d[n/i]*d[m/i];
		}
		printf("%lld\n",ans);
	}
	return 0;
}