Add solution 268

Signed-off-by: Thomas Köhler <jean-luc@picard.franken.de>

4 files changed, 133 insertions, 0 deletions

diff --git a/challenge-268/jeanluc2020/blog-1.txt b/challenge-268/jeanluc2020/blog-1.txt
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+http://gott-gehabt.de/800_wer_wir_sind/thomas/Homepage/Computer/perl/theweeklychallenge-268-1.html
diff --git a/challenge-268/jeanluc2020/blog-2.txt b/challenge-268/jeanluc2020/blog-2.txt
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+http://gott-gehabt.de/800_wer_wir_sind/thomas/Homepage/Computer/perl/theweeklychallenge-268-2.html
diff --git a/challenge-268/jeanluc2020/perl/ch-1.pl b/challenge-268/jeanluc2020/perl/ch-1.pl
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+#!/usr/bin/perl
+# https://theweeklychallenge.org/blog/perl-weekly-challenge-268/#TASK1
+#
+# Task 1: Magic Number
+# ====================
+#
+# You are given two arrays of integers of same size, @x and @y.
+#
+# Write a script to find the magic number that when added to each elements of
+# one of the array gives the second array. Elements order is not important.
+#
+# Example 1
+#
+# Input: @x = (3, 7, 5)
+#        @y = (9, 5, 7)
+# Output: 2
+#
+# The magic number is 2.
+# @x = (3, 7, 5)
+#    +  2  2  2
+# @y = (5, 9, 7)
+#
+# Example 2
+#
+# Input: @x = (1, 2, 1)
+#        @y = (5, 4, 4)
+# Output: 3
+#
+# The magic number is 3.
+# @x = (1, 2, 1)
+#    +  3  3  3
+# @y = (5, 4, 4)
+#
+# Example 3
+#
+# Input: @x = (2)
+#        @y = (5)
+# Output: 3
+#
+############################################################
+##
+## discussion
+##
+############################################################
+#
+# By sorting both arrays, we have each element in each array paired up
+# with the corresponding element of the other array, so the magic number
+# is the difference from one element in one array to its corresponding
+# element in the other array. We can even use this for a sanity check:
+# if the elements don't match up at some point, then no magic number
+# exists
+
+use strict;
+use warnings;
+
+magic_number( [3, 7, 5], [9, 5, 7] );
+magic_number( [1, 2, 1], [5, 4, 4] );
+magic_number( [2], [5] );
+
+sub magic_number {
+   my ($x, $y) = @_;
+   print "Input: (", join(", ", @$x), "), (", join(", ", @$y), ")\n";
+   my @sorted_x = sort { $a <=> $b } @$x;
+   my @sorted_y = sort { $a <=> $b } @$y;
+   die "Both arrays don't have the same length!" unless scalar(@sorted_x) == scalar(@sorted_y);
+   my $magic = $sorted_y[0] - $sorted_x[0];
+   foreach my $idx (0..$#sorted_x) {
+      die "There is no magic number that works for all elements of both arrays!" unless $sorted_x[$idx] + $magic == $sorted_y[$idx];
+   }
+   print "Output: $magic\n";
+}
+
diff --git a/challenge-268/jeanluc2020/perl/ch-2.pl b/challenge-268/jeanluc2020/perl/ch-2.pl
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+#!/usr/bin/perl
+# https://theweeklychallenge.org/blog/perl-weekly-challenge-268/#TASK2
+#
+# Task 2: Number Game
+# ===================
+#
+# You are given an array of integers, @ints, with even number of elements.
+#
+# Write a script to create a new array made up of elements of the given array.
+# Pick the two smallest integers and add it to new array in decreasing order
+# i.e. high to low. Keep doing until the given array is empty.
+#
+## Example 1
+##
+## Input: @ints = (2, 5, 3, 4)
+## Output: (3, 2, 5, 4)
+##
+## Round 1: we picked (2, 3) and push it to the new array (3, 2)
+## Round 2: we picked the remaining (4, 5) and push it to the new array (5, 4)
+#
+## Example 2
+##
+## Input: @ints = (9, 4, 1, 3, 6, 4, 6, 1)
+## Output: (1, 1, 4, 3, 6, 4, 9, 6)
+#
+## Example 3
+##
+## Input: @ints = (1, 2, 2, 3)
+## Output: (2, 1, 3, 2)
+#
+############################################################
+##
+## discussion
+##
+############################################################
+#
+# First, we sort the input array. Then we pick the first two elements
+# in reverse order until there are no more elements in the array.
+
+use strict;
+use warnings;
+
+number_game(2, 5, 3, 4);
+number_game(9, 4, 1, 3, 6, 4, 6, 1);
+number_game(1, 2, 2, 3);
+
+sub number_game {
+   my @ints = @_;
+   print "Input: (", join(", ", @ints), ")\n";
+   my @sorted = sort { $a <=> $b } @ints;
+   my @result = ();
+   while(scalar(@sorted) >= 2) {
+      my $first = shift @sorted;
+      my $second = shift @sorted;
+      push @result, ($second, $first);
+   }
+   print "Output: (", join(", ", @result), ")\n";
+}
+