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PrimesDemo |
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1 // joi/examples/PrimesDemo.java 2 // 3 // 4 // Copyright 1998-2001 Bill Campbell and Ethan Bolker 5 6 // %> java PrimesDemo 7 // 91 false 8 // 101 true 9 10 public class PrimesDemo 11 { 12 public static boolean test( int n ) 13 { 14 if ( n < 0 ) n = -n; 15 if ((n == 1) || (n == 0)) return false; 16 if (n == 2) return true; 17 if (n % 2 == 0 ) return false; 18 double limit = Math.sqrt(n); 19 for (int j = 3; j <= limit; j += 2) { 20 if (n % j == 0) return false; 21 } 22 return true; 23 } 24 25 public static void main( String[] args ) 26 { 27 System.out.println(91 + "\t" + PrimesDemo.test(91)); 28 System.out.println(101 + "\t" + PrimesDemo.test(101)); 29 } 30 } 31
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PrimesDemo |
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