Solutions to challenge 193

2 files changed, 85 insertions, 0 deletions

diff --git a/challenge-193/jo-37/perl/ch-1.sh b/challenge-193/jo-37/perl/ch-1.sh
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+++ b/challenge-193/jo-37/perl/ch-1.sh
@@ -0,0 +1,2 @@
+#!/bin/sh
+perl -se 'printf "%0${n}b\n", $_ for 0..2**$n-1' -- -n=$1
diff --git a/challenge-193/jo-37/perl/ch-2.pl b/challenge-193/jo-37/perl/ch-2.pl
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+++ b/challenge-193/jo-37/perl/ch-2.pl
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+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0;
+use List::MoreUtils 'slide';
+use experimental 'signatures';
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [STR...]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+STR...
+    Print the "odd ones" from the given strings.
+
+EOS
+
+
+### Input and Output
+
+say for pick_odd(@ARGV);
+
+
+### Implementation
+
+# Some thoughts about this task:
+# - There may be more or less than one "odd one".  Regarding a string as
+#   odd if its difference array is unique.
+# - The encoding of letters is irrelevant as long as it is contiguous
+#   because the "difference array" then is independent therefrom.
+# - The strings need not be of equal length.  A differing length gives a
+#   differing "difference array" and thus makes an "odd one".
+
+sub pick_odd {
+    my %odd;
+    # Split the string into an array of integers representing the ASCII
+    # codes of its letters.  Slide over pairs and take the differences.
+    # Store or undefine the string in %odd according to its difference
+    # array as composite key.
+    stou(\%odd, $_, slide {$b - $a} unpack 'c*', $_) for @_;
+
+    # Pick the odd ones.
+    grep defined, values %odd;
+}
+
+# STore Or Undefine:
+# Store the value $val for a nonexisting composite key @key in the hash
+# referenced by $href or remove the value (not the key!) otherwise.
+sub stou ($href, $val, @key) {
+    $href->{"@key"} = exists $href->{"@key"} ? undef : $val;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+        is [pick_odd(qw(adc wzy abc))], ['abc'], 'Example 1';
+        is [pick_odd(qw(aaa bob ccc ddd))], ['bob'], 'Example 2';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+        is [pick_odd(qw(abc abd abe))],
+            bag {item 'abc'; item 'abd'; item 'abe'; end}, 'all odd';
+        is [pick_odd(qw(abcd bcde cdef defg))], [], 'no odd one';
+        is [pick_odd(qw(abm alm))],
+            bag {item 'abm'; item 'alm'; end}, '[1, 11] != [11, 1]';
+        is [pick_odd(qw(aa bb cc ddd))], ['ddd'], 'odd length';
+	}
+
+    done_testing;
+    exit;
+}