CareerCup

void PrintPrimeNo(int n)
{
int i,l;
double j,k;
bool primeNo;
for(i=1; i<=n;i++)
{
primeNo = true;
j=2; k=1.0*i/2;

while(j<=k)
{
l = (int)k;
if((k - (double)l) == 0)
{
primeNo = false;
break;
}
else
{
j++;
k = 1.0*i/j;
}

}
if(primeNo)
cout << i << " ";
}
}

<pre lang="" line="1" title="CodeMonkey55014" class="run-this">Java solution:

public int sumOfPrimes(int n) {
BitSet bitSet = new BitSet(n + 1);
bitSet.set(0, n + 1);
for (int i = 2, last = n / 2; i <= last && i > 0; i = bitSet.nextSetBit(i + 1)) {
for (int j = i + i; j <= bitSet.length(); j += i) {
bitSet.clear(j);
}
}
System.out.println(bitSet.toString()); // Print all primes from 1 up to n

int sum = 0;
int index = 0;
while ((index = bitSet.nextSetBit(++index)) > 0) {
sum += index;
}
System.out.println(sum);
}</pre>

<pre lang="" line="1" title="CodeMonkey26398" class="run-this">Java solution:

public int sumOfPrimes(int n) {
BitSet bitSet = new BitSet(n + 1); // one extra bit to save many -1 operations
bitSet.set(1, n);
for (int i = 2, last = n / 2; i <= last && i > 0; i = bitSet.nextSetBit(i + 1)) {
for (int j = i + i; j <= bitSet.length(); j += i) {
bitSet.clear(j);
}
}
System.out.println(bitSet.toString()); // Print all primes from 1 up to n

int sum = 0;
int index = 0;
while ((index = bitSet.nextSetBit(++index)) > 0) {
sum += index;
}
System.out.println(sum);
}</pre>

wiki Sieve_of_Eratosthenes

#include<stdio.h>

int main()
{
int i,j;
Read n;
for (i=2; i<n; i++)
{
j=2;
while(j<i)
{
if(i%j==0)
break;

j++;
}
if(j==i)
printf("%d ",i);
}

return 0;
}

public class ArithmaticOperation {
public static void main(String[] args) {

int num = 4;

primeNumber(num);
}

private static void primeNumber(int num) {

boolean bNotPrime = false;
if(num==2 || num==3 || num==5){
System.out.println(num + " is a prime number...");
return;
}
for(int i=2;i<=num/2;i++){
if(num%i == 0)
bNotPrime = true;
}

if(!bNotPrime)
System.out.println(num + " is a prime number...");
else
System.out.println(num + " is NOT a prime number...");
}

}

public class Prime
{ public static void main(String a[])
{
int i=0,j=0;
boolean prime=true;
int n=25;
for (i=1;i<n;i++)
{
prime=true;
for(j=2;j<=Math.sqrt(i);j++)
{
if(i%j==0)
prime=false;
}
if (prime==true)
System.out.println(i);
}
}
}

SieveOfEathonse

namespace PrimeNumbersListSieveOfEathonse
{
    class Program
    {
        private static int upperLimit = 10000;
        private static Boolean[] flags;
        static void Main(string[] args)
        {

            findPrimes(upperLimit);
                displayPrimes();
            Console.ReadKey();
            }

            private static void findPrimes(int number)
            {

                int upperLimit = number;
                
               flags = new Boolean[upperLimit + 1];
                for (int position = 0; position <= upperLimit; position++)
                {
                    flags[position] = false;
                }
                for (int position = 2; position <= Math.Sqrt(upperLimit); position++)
                {
                    if (!flags[position])
                    {
                        int multiple = position * 2;
                        while (multiple <= upperLimit)
                        {
                            flags[multiple] = true;
                            multiple += position;
                        }
                    }
                }
            }

            private static void displayPrimes() {
        for (int position = 2; position <= upperLimit; position++) { 
            if (!flags[position]) { 
                Console.WriteLine(position + ", "); 
            } 
        }     
    }

        }
    }

import java.util.LinkedList;
import java.util.List;
import java.util.Scanner;

public class PrimeTest2 {

/**
* @param args
*/
public static void main(String[] args) {

int count=0, p, numberOfPrimes;
List<Integer> primeList = new LinkedList<Integer>();

System.out.print("Enter the number of primes you want to get: ");
Scanner scan = new Scanner(System.in);
while(true){
if(!scan.hasNextInt()){
System.out.print("please enter only integer: ");
scan.next();
continue;
}else{
numberOfPrimes = scan.nextInt();
break;
}
}
p=1;
while(count<numberOfPrimes){
if(checkPrime(p)){
primeList.add(p);
count++;
}
p++;
}
System.out.println("First "+numberOfPrimes+" primes: "+primeList);
}

public static boolean checkPrime(int x){
if(x==1 || x ==2) return true;
if(x%2==0) return false;
int k=3;
int a=x/k+x%k;
while(k<=a){
if(x%k==0){
return false;
}else{
k+=2;
a = x/k+x%k;
}
}
return true;
}
}