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//
// SIEVE. The Sieve of Eratosthenes.
//
// James B. Moen
// 08 Oct 19
//
// Test the SIEVE class, for 30 points total.
//
//
// Put your code for the class SIEVE here!!!
//
class Sieve {
private boolean[] numbers;
private int realMax;
public Sieve(int max){
if (max<2)
throw new IllegalArgumentException();
numbers = new boolean[max];
realMax = (max - 1);
for (int i=2; i<max; i+=1) { numbers[i]=true; }
}
public void findPrimes() {
for (int i=2; i<=realMax; i+=1) {
//Only look for composite numbers if the number is prime
if (numbers[i]) {
for (int j=(i*2); j<=realMax; j+=i) {
numbers[j]=false;
}
}
// System.out.println(i);
}
}
public String toString(){
String str = "";
for (int n = 0; n <= realMax; n += 1) {
if (numbers[n]) {
str += n; str += " ";
}
}
return str;
}
}
// TOSS THE KNEES. Run SIEVE on some examples.
class TossTheKnees
{
// MAIN. Find some primes.
public static void main(String [] args)
{
Sieve sieve = null; // We must initialize SIEVE or Java will cry.
// 5 points. This must print "Sieve size must be at least 2." but without the
// quotes.
try
{
sieve = new Sieve(0);
}
catch (IllegalArgumentException oops)
{
System.out.println("Sieve size must be at least 2.");
}
// 5 points. This must print nothing.
try
{
sieve = new Sieve(100);
}
catch (IllegalArgumentException oops)
{
System.out.println("Sieve size must be at least 2.");
}
// 10 points. This must print integers from 2 to 99, separated by blanks.
System.out.println(sieve);
// 10 points. This must print the prime numbers between 2 and 99, separated by
// blanks. They are:
//
// 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
sieve.findPrimes();
System.out.println(sieve);
}
}
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