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  1. #!/usr/bin/perl
  2. use strict;
  3. use warnings;
  4.  
  5. my $magic = 7393913335919140050521110339491123405991919445111971;
  6.  
  7. sub largestprimef($);
  8. sub max($$);
  9.  
  10. print largestprimef($magic);
  11.  
  12. sub largestprimef($) {
  13.     my $n = shift;
  14.  
  15.     my $i;
  16.     return largestprimef(max(2, $n/2)) if($n % 2 == 0); 
  17.     my $sn = int( sqrt($n) );
  18.  
  19.     for ( $i = 3 ; $i <= $sn ; $i += 2 ) {
  20.         if ( $n % $i == 0 ) { last; }
  21.     }
  22.     if ( $i > $sn )    #loop ran over, means the number is prime
  23.     {
  24.         return $n;
  25.     }
  26.     else {
  27.         return max( $i, largestprimef( $n / $i ) );
  28.     }
  29. }
  30.  
  31. sub max($$) {
  32.     return ( sort { $a <=> $b } (@_) )[1];
  33. }
Success #stdin #stdout #stderr 0.82s 6128KB
comments (?)
stdin 
Standard input is empty
stdout 
22704335299507
stderr 
Deep recursion on subroutine "main::largestprimef" at prog.pl line 16.
https://ideone.com/eaneoq
language:
Perl (perl 5.28.1)
created:
10 years ago
visibility:
public

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