/* Computes prime numbers within a given range.  Adapted from 
   pthreads program published at 
   http://docs.sun.com/app/docs/doc/820-0619/6ncbk8g6q?a=view
*/
public class PrimeBuggy implements Runnable {
    private static int start, N;
    private static int numThreads;
    private static int primes[];
    private static boolean pflag[];
    private static int total = 0;

    private static boolean is_prime(int v) {
        int i;
        int bound = (int)Math.floor(Math.sqrt((double)v)) + 1;
        for (i = 2; i < bound; i++) {
            if (pflag[i])
                continue;
            if (v % i == 0) {
                pflag[v] = true;
                return false;
            }
        }
        return (v > 1);
    }    

    /***/
    private int threadNum;
    private PrimeBuggy(int threadNum) { this.threadNum = threadNum; }
    public void run() {
        int i;
        start = N/numThreads * threadNum;
        N = start + N/numThreads;
        for (i = start; i < N; i++) {
            if (is_prime(i)) {
                primes[total] = i;
                total++;
            }
        }
    }

    public static void main(String args[]) throws InterruptedException {
        if (args.length != 2) {
            System.out.println("Args: numPrimes numThreads");
            System.exit(1);
        }

        N = new Integer(args[0]).intValue();
        primes = new int[N];
        pflag = new boolean[N];

        numThreads = new Integer(args[1]).intValue();
        Thread[] threads = new Thread[numThreads-1];

        for (int i = 0; i<numThreads; i++) {
            if (i != numThreads-1) {
                threads[i] = new Thread(new PrimeBuggy(i));
                threads[i].start();
            }
            else {
                new PrimeBuggy(i).run();
            }
        }

        System.out.println("Number of prime numbers between 2 and "+N+
                           ": "+total);
        //        for (int i = 0;i< total; i++) {
        //   System.out.println(primes[i]);
        //}
    }
}