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  1. import java.util.Iterator;
  2.  
  3. final class Ideone {
  4.  
  5.   private static Iterable<Integer> primes(final int n) {
  6.     final boolean[] composite = new boolean[n+1];
  7.     for (int i = 2; i <= n; ++i) {
  8.       if (!composite[i]) {
  9.         for (int j = i * i; j <= n; j += i) {
  10.           composite[j] = true;
  11.         }
  12.       }
  13.     }
  14.     return new Iterable<Integer>() {
  15.  
  16.       public Iterator<Integer> iterator() {
  17.         return new Iterator<Integer>() {
  18.           int cur = 1;
  19.  
  20.           public Integer next() {
  21.             while (cur <= n && composite[cur++]) ;
  22.             return cur - 1;
  23.           }
  24.  
  25.           public boolean hasNext() {
  26.           	int p = cur;
  27.           	while (p <= n && composite[p++]) ;
  28.           	return p <= n;
  29.           }
  30.         };
  31.       }
  32.     };
  33.   }	
  34.  
  35.   public static void main(final String[] argv) {
  36.     for (final int p : primes(100)) {
  37.     	System.out.println(p);
  38.     }
  39.   }
  40. }
Success #stdin #stdout 0.1s 320320KB
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https://ideone.com/JKA2ik
language:
Java (HotSpot 12)
created:
10 years ago
visibility:
secret

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