Project Euler 問題29

pe_29.pl

#!/usr/bin/perl

use strict;
use warnings;
use Math::BigInt;

my ($amin, $amax, $bmin, $bmax) = @ARGV; # 2 100 2 100
my $len = length((Math::BigInt->new($amax)**$bmax)->as_hex()) - 2;
my %arr;
my $v;

for(my $i=$amin; $i<=$amax; $i++)
{
  for(my $j=$bmin; $j<=$bmax; $j++)
  {
    $v = (Math::BigInt->new($i) ** $j)->as_hex(); #prefix '0x'
    $v = substr($v, 2);
    $v = sprintf("%0".$len."s", $v);
    #print "$v\n";
    $arr{$v} = 1;
  }
}
my @arr = sort {$a cmp $b} keys %arr;
print "($amin<=a<=$amax, $bmin<=b<=$bmax) Ans: ".(scalar @arr)."\n";

#(2<=a<=100, 2<=b<=100) Ans: 9183

32bit OS だと use bigint はダメなのね...