Create ch-1.pl

1 files changed, 47 insertions, 0 deletions

diff --git a/challenge-198/james-smith/perl/ch-1.pl b/challenge-198/james-smith/perl/ch-1.pl
new file mode 100644
index 0000000000..371a2c4d13
--- /dev/null
+++ b/challenge-198/james-smith/perl/ch-1.pl
@@ -0,0 +1,47 @@
+#!/usr/local/bin/perl
+
+use strict;
+use warnings;
+use feature qw(say);
+use Test::More;
+use Benchmark qw(cmpthese timethis);
+
+my @TESTS = (
+  [ [2,5,8,1                         ], 2 ],
+  [ [3                               ], 0 ],
+  [ [1..9,21..25, map { 2*$_ } 5..10 ], 5 ],
+  [ [(1) x 10                        ], 9 ],
+  [ [ 1..10                          ], 9 ],
+  [ [ 2.9 , 3..10                    ], 7],
+  [ [ 1..8,8.1                       ], 7],
+  [ [ 1, 3..10                       ], 1 ],
+  [ [ 1..8, 10                       ], 1 ],
+  [ [ 1..999, 1001                   ], 1 ],
+  [ [ 1..999, 999.1                  ], 998 ],
+);
+
+is( max_gap_sort(    @{$_->[0]} ), $_->[1] ) for @TESTS;
+is( max_gap_nosort(  @{$_->[0]} ), $_->[1] ) for @TESTS;
+done_testing();
+
+cmpthese( -10, {
+  'sort'   => sub { max_gap_sort(   @{$_->[0]} ) for @TESTS }, # 1700/s
+  'nosort' => sub { max_gap_nosort( @{$_->[0]}) for @TESTS },  # 3535/s
+} );
+
+sub max_gap_sort {
+  return 0 unless $#_;
+  @_ = sort { $a <=> $b } @_;
+  my $p = shift;
+  @_ = sort { $b <=> $a } map { ($_-$p,$p=$_)[0] } @_;
+  $_[0]==$_[$_] || return $_ for 1..$#_;
+  1*@_
+}
+
+sub max_gap_nosort {
+  return 0 unless $#_;
+  @_ = sort { $a <=> $b } @_;
+  my($p,$b,$c)=(shift,0,0);
+  $_-$p>$b ? ($b,$c)=($_-$p,1) : $_-$p==$b && $c++, $p=$_ for @_;
+  $c;
+}