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segmentedsieve.java
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79 lines (77 loc) · 1.98 KB
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import java.util.*;
public class segmentedsieve {
static int MAX =10000001;
static ArrayList<Integer> sieve()
{
boolean isp[]=new boolean[MAX];
Arrays.fill(isp,true);
ArrayList<Integer> primes=new ArrayList<>();
for(int i=2;i*i<MAX;i++)
{
if(isp[i])
{
for(int j=i*i;j<MAX;j+=i)
{
isp[j]=false;
// primes.add(j);
}
}
}
primes.add(new Integer("2"));
for(int i=3;i<MAX;i++)
{
if(isp[i])
primes.add(i);
}
return primes;
}
static long segsieve(int l,int r,ArrayList<Integer> primes)
{
long prod=1;
long p=1000000007;
int base=0;
boolean pr[]=new boolean[r-l+1];
Arrays.fill(pr,true);
int currprime=0;
for(int i=0;primes.get(i)*(long)primes.get(i)<=r;i++)
{
currprime=primes.get(i);
base=(l/currprime)*currprime;
if(base<l)
base+=currprime;
for(int j=base;j<=r;j+=currprime)
{
pr[j-l]=false;
}
if(base==currprime)
{
pr[base-l]=true;
}
}
long count=-1;
for(int i=0;i<=(r-l);i++)
{
if(pr[i]==true)
{
prod=((prod%p)*((i+l)%p))%p;
}
}
return prod;
}
public static void main(String args[])
{
Scanner in=new Scanner(System.in);int t=0,l=0,r=0;
if(in.hasNext())
t=in.nextInt();
ArrayList<Integer> primes;
primes=sieve();
for(int j=0;j<t;j++)
{
if(in.hasNext())
l=in.nextInt();
if(in.hasNext())
r=in.nextInt();
System.out.println(segsieve(l,r,primes));
}
}
}