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| -rwxr-xr-x | challenge-138/jo-37/perl/ch-2.pl | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/challenge-138/jo-37/perl/ch-2.pl b/challenge-138/jo-37/perl/ch-2.pl new file mode 100755 index 0000000000..bf1930ebec --- /dev/null +++ b/challenge-138/jo-37/perl/ch-2.pl @@ -0,0 +1,87 @@ +#!/usr/bin/perl -s + +use v5.16; +use Test2::V0; +use experimental 'signatures'; + +our ($tests, $examples); + +run_tests() if $tests || $examples; # does not return + +die <<EOS unless @ARGV; +usage: $0 [-examples] [-tests] [N] + +-examples + run the examples from the challenge + +-tests + run some tests + +N + Check if the square root of N is the sum of two or more splits of N + +EOS + + +### Input and Output + +say 0 + root_sum(shift); + + +### Implementation + +sub root_sum ($n) { + # Split N into at least two parts and compare the squared sum of the + # parts with N. + # There is no need to disallow leading zeros in any part (except the + # first), as these may be split-off as separate parts resulting in + # the same sum and a larger number of parts, e.g. + # 201: 2 + 01 or 2 + 0 + 1. + # The only exception are single digit numbers that cannot be split + # into two parts and therefore must not have leading zeros. + our $sum; + $n =~ m{ + ^ + (?=\d+$) # Numbers only. + (?!0+.$) # Forbid leading zeros for 1-digit numbers. + (?{local $sum = 0}) # Initialize and localize the part sum. + (?: + (.+) # capture one part + (?{local $sum = $sum + $^N}) # backtracking-safe part sum + ){2,} # two or more parts + $ + + # Check part sum for complete matches: + (?(?{$sum ** 2 != $n}) (*FAIL)) + }x; +} + + +### Examples and tests + +sub run_tests { + SKIP: { + skip "examples" unless $examples; + + is root_sum(81), T(), 'example 1'; + is root_sum(9801), T(), 'example 2'; + is root_sum(36), F(), 'example 3'; + } + + SKIP: { + skip "tests" unless $tests; + + is root_sum(1296), T(), 'without zeros'; + is root_sum(18), F(), 'not a square'; + is root_sum(0), F(), 'zero'; + is root_sum('00'), F(), 'double zero'; + is root_sum(1), F(), 'one'; + is root_sum('01'), F(), 'one with leading zero'; + is root_sum('001'), F(), 'one with leading zeros'; + is root_sum('081'), T(), 'leading zero'; + is root_sum(-abc), F(), 'non-numeric'; + } + + done_testing; + exit; +} |