prime number java Sieve of Eratosthenes code example
Example 1: sieve in java
class SieveOfEratosthenes
{
void sieveOfEratosthenes(int n)
{
boolean prime[] = new boolean[n+1];
for(int i=0;i<n;i++)
prime[i] = true;
for(int p = 2; p*p <=n; p++)
{
if(prime[p] == true)
{
for(int i = p*p; i <= n; i += p)
prime[i] = false;
}
}
for(int i = 2; i <= n; i++)
{
if(prime[i] == true)
System.out.print(i + " ");
}
}
public static void main(String args[])
{
int n = 30;
System.out.print("Following are the prime numbers ");
System.out.println("smaller than or equal to " + n);
SieveOfEratosthenes g = new SieveOfEratosthenes();
g.sieveOfEratosthenes(n);
}
}
Example 2: prime of sieve
#include<iostream>
#include<math.h>
using namespace std;
void primeofsieve(long long int n)
{
long long int arr[n]={};
for(int i=2;i<=sqrt(n);i++)
{
for(long long int j=i*i;j<=n;j+=i)
arr[j]=1;
}
for(long long int i=2;i<=n;i++)
{
if(arr[i]==0)
cout<<i<<" ";
}
}
int main()
{
#ifdef _DEBUG
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
long long int n;
cin>>n;
cout<<"PRIME NUMBERs ARE : ";
primeofsieve(n);
return 0;
}