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| -rw-r--r-- | challenge-221/cheok-yin-fung/perl/ch-2.pl | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/challenge-221/cheok-yin-fung/perl/ch-2.pl b/challenge-221/cheok-yin-fung/perl/ch-2.pl new file mode 100644 index 0000000000..99c91e8982 --- /dev/null +++ b/challenge-221/cheok-yin-fung/perl/ch-2.pl @@ -0,0 +1,27 @@ +# The Weekly Challenge 221 +# Task 2 Arithmetic Subsequence +# Brute-force approach, just hope the number of lines is minimalist +use v5.30.0; +use warnings; +use List::Util qw/all sum uniqint/; +use List::MoreUtils qw/slide/; + +sub as { + my @arr = @_; + return 1 if scalar @arr == 1; + my $len_of_longest_as = 2; + for my $i (reverse 7..2**($#arr+1)-1) { + my $l = length sprintf("%0b", $i); + my @bin = split "", "0" x ($#arr+1-$l).sprintf("%0b", $i); + next if sum (@bin) < $len_of_longest_as; + my @n_arr = map {$arr[$_]} grep {$bin[$_]} (0..$#arr); + my @diffs = slide {$a-$b} @n_arr; + $len_of_longest_as = sum (@bin) if scalar (uniqint @diffs) == 1; + } + return $len_of_longest_as; +} + +use Test::More tests=> 3; +ok as(9, 4, 7, 2, 10) == 3; +ok as(3, 6, 9, 12) == 4; +ok as(20, 1, 15, 3, 10, 5, 8) == 4; |