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| -rw-r--r-- | challenge-287/jtimothyking/perl/ch-1.pl | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/challenge-287/jtimothyking/perl/ch-1.pl b/challenge-287/jtimothyking/perl/ch-1.pl new file mode 100644 index 0000000000..ed9b7c50db --- /dev/null +++ b/challenge-287/jtimothyking/perl/ch-1.pl @@ -0,0 +1,59 @@ +#!/usr/bin/perl +use v5.38; +use warnings; + +use List::Util qw(max); + +my $password = shift // 'Paaasw0rd'; + +# Minimum length is 6 characters. +my $num_chars_needed = 6 - length($password); +# We never need to delete characters in order to satisfy the minimum length. +$num_chars_needed = 0 if ($num_chars_needed < 0); + +# We need at least one character from each of the following character classes. +my $is_lowercase = $password =~ /[a-z]/; +my $is_uppercase = $password =~ /[A-Z]/; +my $is_digit = $password =~ /\d/; +my $num_classes_needed = !$is_lowercase + !$is_uppercase + !$is_digit; + +# We need to assure that at most two characters repeat in a row. +my $num_replacements_needed = 0; +# Find sequences of characters that repeat at least 3 times. +while ($password =~ /((.)\2{2,})/g) { + # We need to replace each third repeated character in order to make sure + # at most only two characters repeat in a row. + $num_replacements_needed += int(length($1) / 3); +} + +# Here's where a nifty optimization comes into play: +# We can add additional character classes by adding chars or by making +# replacements to the existing password. Additionally, we can reduce the +# number of replacements needed by inserting characters rather than +# changing existing ones and appending characters. +# Consider: +# - If the password is 4 characters or less, we need to add at least 2 +# characters. We will choose the new characters to be from the missing +# classes. $num_chars_needed >= $num_classes_needed, and we will use +# $num_chars_needed as the number of steps. +# - If the password is 3 or 4 *repeating* characters, we will insert +# at least one character instead of appending, so we don't need to +# replace any existing characters. +# $num_chars_needed > $num_replacements_needed, and we will use +# $num_chars_needed as the number of steps. +# - If the password is 5 repeating characters, we will replace one of +# the characters and insert one new character, each from a missing +# class. $num_chars_needed > $num_classes_needed and +# $num_chars_needed > $num_replacements_needed, and we will use +# $num_chars_needed as the number of steps. +# - If the password is 6 or more repeating characters, we will replace +# at least two of the characters, each from a missing class. +# $num_replacements_needed >= $num_classes_needed, and we will use +# $num_replacements_needed as the number of steps. +# In other words, we only need to choose the maximum of the three values +# as the number of steps. +my $num_steps = max($num_chars_needed, $num_classes_needed, $num_replacements_needed); + +say $num_steps; + +__END__ |