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  1. public class CoprimeNeighbors {
  2. long gcd(long a, long b) {
  3. return a == 0 ? b : gcd(b % a, a);
  4. }
  5. final long BIL = 1000 * 1000 * 1000;
  6. boolean isPrime(int a) {
  7. for(int i = 2; i * i <= a; ++i)
  8. if(a % i == 0)
  9. return false;
  10. return true;
  11. }
  12. // find first 'cnt' primes
  13. int[] findPrimes(int cnt) {
  14. int[] primes = new int[cnt];
  15. int next = 2;
  16. for(int i = 0; i < cnt; ++i) {
  17. while(!isPrime(next))
  18. ++next;
  19. primes[i] = next++;
  20. }
  21. return primes;
  22. }
  23. // return product of 'k' random primes
  24. static Random rand = new Random();
  25. long randomNumber(int[] primes, boolean[] forbidden, int k) {
  26. int n = primes.length;
  27. boolean[] taken = new boolean[n];
  28. long x = 1;
  29. for(int repeat = 0; repeat < k; ++repeat) {
  30. int i;
  31. do {
  32. i = rand.nextInt(n);
  33. } while(taken[i] || forbidden[i]);
  34. taken[i] = true;
  35. long product = x * primes[i];
  36. if(product / primes[i] != x || product > BIL * BIL) {
  37. System.out.println("exceed");
  38. return randomNumber(primes, forbidden, k); // 1e18 exceeded, try again
  39. }
  40. x *= primes[i];
  41. }
  42. return x;
  43. }
  44. public long[] findAny(int len) {
  45. final int x = 32, y = 11;
  46. long[] t = new long[len];
  47. int[] primes = findPrimes(x);
  48. System.out.println(Arrays.toString(primes));
  49. for(int i = 0; i < len; ++i) {
  50. boolean[] forbidden = new boolean[x];
  51. if(i != 0)
  52. for(int j = 0; j < x; ++j)
  53. if(t[i-1] % primes[j] == 0)
  54. forbidden[j] = true;
  55. while(true) {
  56. t[i] = randomNumber(primes, forbidden, y);
  57. boolean ok = true;
  58. for(int j = 0; j < i - 1; ++j)
  59. if(gcd(t[j], t[i]) == 1)
  60. ok = false;
  61. if(ok) break;
  62. System.out.println("gcd");
  63. }
  64. }
  65. return t;
  66. }
  67. }
  68.  
Compilation error #stdin compilation error #stdout 0s 0KB
stdin
Standard input is empty
compilation info
Main.java:7: error: class CoprimeNeighbors is public, should be declared in a file named CoprimeNeighbors.java
public class CoprimeNeighbors {
       ^
1 error
stdout

Standard output is empty