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  1. #!/usr/bin/perl
  2. use 5.016;
  3. use warnings;
  4.  
  5. package _Stream;
  6.  
  7. sub new {
  8. 	my $class = shift;
  9. 	return bless [ @_ ], $class;
  10. }
  11.  
  12. sub value { $_[0]->[0] }
  13. sub next { ref $_[0]->[1] eq 'CODE' ? $_[0]->[1] = $_[0]->[1]->() : $_[0]->[1] }
  14.  
  15. package main;
  16.  
  17. my @dir = ([1, 0], [0, 1], [-1, 0], [0, -1]);
  18.  
  19. sub f1 {
  20. 	my ($x, $y, $l, $c, $d) = @_;
  21.  
  22. 	my ($dx, $dy) = @{$dir[$d]};
  23.  
  24. 	return _Stream->new(
  25. 		[$x, $y],
  26. 		(($c < 1) ?
  27. 			sub{ f2($x + $dx, $y + $dy, $l + 1, $l + 1, ($d + 1) % 4) } :
  28. 			sub{ f1($x + $dx, $y + $dy, $l, $c - 1, $d) }
  29. 		)
  30. 	);
  31. }
  32.  
  33. sub f2 {
  34. 	my ($x, $y, $l, $c, $d) = @_;
  35.  
  36. 	my ($dx, $dy) = @{$dir[$d]};
  37.  
  38. 	return _Stream->new(
  39. 		[$x, $y],
  40. 		(($c < 1) ?
  41. 			sub{ f1($x + $dx, $y + $dy, $l, $l, ($d + 1) % 4) } :
  42. 			sub{ f2($x + $dx, $y + $dy, $l, $c - 1, $d) }
  43. 		)
  44. 	);
  45. }
  46.  
  47. sub f { f2(0, 0, 0, 0, 0) }
  48.  
  49. sub is_prime {
  50. 	my ($n) = @_;
  51.  
  52. 	($n < 2) and return 0;
  53. 	($n == 2) and return 1;
  54. 	($n % 2 == 0) and return 0;
  55.  
  56. 	for(my $i = 3; $i <= $n / $i; $i += 2){
  57. 		($n % $i == 0) and return 0;
  58. 	}
  59.  
  60. 	return 1;
  61. }
  62.  
  63. sub g {
  64. 	my $o = int(shift() / 2);
  65. 	my $n = ($o * 2 + 1) ** 2;
  66.  
  67. 	my @d;
  68. 	my $f = f();
  69. 	foreach(1 .. $n){
  70. 		my ($x, $y) = @{$f->value};
  71. 		$f = $f->next;
  72. 		$d[$o - $y]->[$o + $x] = (is_prime($_) ? '*' : ' ');
  73. 	}
  74.  
  75. 	return @d;
  76. }
  77.  
  78. foreach(g(79)){
  79. 	say @{$_};
  80. }
  81.  
Success #stdin #stdout 0.07s 4000KB
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https://ideone.com/Mc2Q9F
language:
Perl (perl 5.28.1)
created:
11 years ago
visibility:
public

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