#include <iostream.h>

void prime_num(int num,int cut);
void center_list(int primes[],int len, int c,int n);


void main()
{
	int N,C;

	cin>>N>>C;
	
	while(N>0)
	{
		prime_num(N,C);
		cin>>N>>C;

	}
}

void prime_num( int num,int cut)
{
	int prime_list[169],k=0,i;
	bool isPrime=true;
	
	for(i=1;i<169;i++)
	{
		prime_list[i]=0;
	}

	for ( i = 1; i <= num; i++)
	{
			for ( int j = 2; j <i; j++)
			{
					if ( i % j == 0 )
					{
					  isPrime=false;
					  break;
					}
			}
			if (isPrime)
			{
			  prime_list[k]=i;
			  k++;

			}
			isPrime=true;
	}
	center_list(prime_list,k,cut,num);
}

void center_list(int primes[169],int len,int c,int n)
{
	int pos,cut_len,i;

	if(len%2==0)
	{
		cut_len=c*2;	
	}
	else
	{
		cut_len=c*2-1;
	}
	
	pos=(len-cut_len)/2;

	cout<<n<<" "<<c<<":";	
	
	if(cut_len<=len)
	{
		for (i = 0; i < cut_len; i++)
		{
			cout<<" "<<primes[pos+i];
		}
		cout<<"\n\n";

	}
	else
	{
		for (i = 0; i < len; i++)
		{
			cout<<" "<<primes[pos+i];
		}
		cout<<"\n\n";
	}

}

Hello everyone! I have written the above code. The purpose is tofindthe prime numbers of a givennumber (N) put them in a list . Then cut the center list of length C*2 or C*2-1 and print it. Everything works ok but I need to make my programm faster. Any ideasplease??????

Salem commented: Thanks for using code tags, so many newbies fail at this step +9

Thnx a lot vijayan121 !!

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