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| -rwxr-xr-x | challenge-160/jo-37/perl/ch-1.pl | 105 | ||||
| -rwxr-xr-x | challenge-160/jo-37/perl/ch-2.pl | 70 |
2 files changed, 175 insertions, 0 deletions
diff --git a/challenge-160/jo-37/perl/ch-1.pl b/challenge-160/jo-37/perl/ch-1.pl new file mode 100755 index 0000000000..d89dc045b7 --- /dev/null +++ b/challenge-160/jo-37/perl/ch-1.pl @@ -0,0 +1,105 @@ +#!/usr/bin/perl -s + +use v5.16; +use Test2::V0; +use Lingua::EN::Nums2Words; +use experimental 'signatures'; + +our ($tests, $examples); + +Lingua::EN::Nums2Words::set_case('lower'); + +run_tests() if $tests || $examples; # does not return + +die <<EOS unless @ARGV; +usage: $0 [-examples] [-tests] [N] + +-examples + run the examples from the challenge + +-tests + run some tests + +N + Explain N. + +EOS + + +### Input and Output + +say four_is_magic(shift); + + +### Implementation + +# I avoided any web research on the topic and came to this conclusion: +# Here a "magic number" is a number that equals the length of its English +# cardinal representation. Obviously, four is magic and it's the only +# magic number below ten. One can assume that the English cardinal +# representation's length is bound by C * log10(N) and thus there cannot +# be any large magic number. Given that there is no other magic number +# below 1000, four is the only magic number and the sequence obtained by +# repeated application of the representational length operation must +# always lead to four. +# +# The task states: "You are given a positive number, $n < 10". I do not +# see any reason to exclude zero and from the considerations above there +# is no need to restrict N to be less than ten. Thus generalizing the +# task to any non-negative integer. + +sub four_is_magic ($n) { + # Sanity check. + die "not an integer" unless $n =~ /^\d+$/; + # Substitute a non-magic number at the end of the string with its + # "explanation" followed by its representational length until the + # magic number four is reached. + 1 while $n =~ s{ + ^\D*\K # Keep the string's starting text. + (?!4$) # Stop at the magic four. + (\d+)$ # Capture a number at the end of the string. + } + { + my $word = num2word $1; + my $len = length $word; + "$word is @{[num2word $len]}, $len" # generate an explanation + }ex; + + # Explain the magic number and titlecase the result. + $n =~ s/^(\D*)(\d+)$/"\u$1@{[num2word $2]} is magic."/er +} + + +### Examples and tests + +sub run_tests { + SKIP: { + skip "examples" unless $examples; + + is four_is_magic(5), + 'Five is four, four is magic.', 'example 1'; + + is four_is_magic(7), + 'Seven is five, five is four, four is magic.', 'example 2'; + + is four_is_magic(6), + 'Six is three, three is five, five is four, four is magic.', + 'example 3'; + } + + SKIP: { + skip "tests" unless $tests; + + is four_is_magic(4), 'Four is magic.', 'Four is magic.'; + is four_is_magic(100), + 'One hundred is eleven, eleven is six, six is three, three is five, five is four, four is magic.', + 'one hundred'; + + is four_is_magic(88666), + 'Eighty-eight thousand, six hundred sixty-six is forty-four, forty-four is ten, ten is three, three is five, five is four, four is magic.', + 'contains 44'; + } + + done_testing; + exit; +} diff --git a/challenge-160/jo-37/perl/ch-2.pl b/challenge-160/jo-37/perl/ch-2.pl new file mode 100755 index 0000000000..0a1676d306 --- /dev/null +++ b/challenge-160/jo-37/perl/ch-2.pl @@ -0,0 +1,70 @@ +#!/usr/bin/perl -s + +use v5.16; +use Test2::V0; +use List::Util 'sum0'; + +our ($tests, $examples); + +run_tests() if $tests || $examples; # does not return + +die <<EOS unless @ARGV; +usage: $0 [-examples] [-tests] [--] [I1 I2 ...] + +-examples + run the examples from the challenge + +-tests + run some tests + +I1 I2 ... + List of integers. + +EOS + + +### Input and Output + +say equilibrium_index(@ARGV); + + +### Implementation + +# The task does not specify if empty subarrays are allowed. Assuming +# they are allowed and have a sum of zero. +sub equilibrium_index { + my ($i, $left, $right) = (0, 0, sum0 @_[1 .. $#_]); + # Starting with an empty left subarray, shift the index until an + # equilibrium is found or the right subarray becomes empty. + while ($left != $right && $i < $#_) { + $left += $_[$i++]; + $right -= $_[$i]; + } + + $left == $right ? $i : -1; +} + + +### Examples and tests + +sub run_tests { + SKIP: { + skip "examples" unless $examples; + + is equilibrium_index(1, 3, 5, 7, 9), 3, 'example 1'; + is equilibrium_index(1, 2, 3, 4, 5), -1, 'example 2'; + is equilibrium_index(2, 4, 2), 1, 'example 3'; + } + + SKIP: { + skip "tests" unless $tests; + + is equilibrium_index(1, 1, 1, 3, -1), 2, 'negative element'; + is equilibrium_index(1, -1, 2), 2, 'empty right subarray'; + is equilibrium_index(2, 1, -1), 0, 'empty left subarray'; + is equilibrium_index(1), 0, 'two empty subarrays'; + } + + done_testing; + exit; +} |