/*
  Prime100
  written by Keith Fenske
  Monday, 22 April 2002
  Copyright (c) 2002 by Keith Fenske.  All rights reserved.

  This is a simple Java application to compute all prime numbers less than
  100 using the algorithm on page 22 of "Discrete Mathematical Structures".

  The algorithm is not smart because it tests all numbers from 2 to 99, and
  all possible odd divisors less than the square root of n.
*/

public class Prime100
{
  public static void main(String[] args)
  {
    boolean flag;                 // true if n is prime
    int d;                        // divisor to test
    int k;                        // largest integer less than square root
    int n;                        // number we are checking if prime

    System.out.println("Prime numbers less than 100:");
    for (n = 2; n < 100; n ++)    // try all numbers from 2 to 99
    {
      if (n == 2)
        flag = true;              // 2 is prime
      else if ((n % 2) == 0)
        flag = false;             // even numbers are not prime
      else
      {
        flag = true;              // assume n is prime
        k = (int) Math.sqrt((double) n);
        for (d = 3; d <= k; d = d + 2)
        {
          if ((n % d) == 0)       // does d divide n?
            flag = false;         // yes, n is not prime
        }
      }
      if (flag)                   // is this number prime?
        System.out.print(n + "  ");
    }
  }
}