Merge pull request #9878 from MatthiasMuth/muthm-263

Challenge 263 Task 1 and 2 solutions in Perl by Matthias Muth

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diff --git a/challenge-263/matthias-muth/blog.txt b/challenge-263/matthias-muth/blog.txt
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+https://github.com/MatthiasMuth/perlweeklychallenge-club/tree/muthm-263/challenge-263/matthias-muth#readme
diff --git a/challenge-263/matthias-muth/perl/README.md b/challenge-263/matthias-muth/perl/README.md
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+# Indexes and Items
+**Challenge 263 solutions in Perl by Matthias Muth**
+
+## Task 1: Target Index
+
+> You are given an array of integers, @ints and a target element $k.<br/>
+> Write a script to return the list of indices in the sorted array where the element is same as the given target element.<br/>
+> <br/>
+> Example 1<br/>
+> Input: @ints = (1, 5, 3, 2, 4, 2), $k = 2<br/>
+> Output: (1, 2)<br/>
+> Sorted array: (1, 2, 2, 3, 4, 5)<br/>
+> Target indices: (1, 2) as $ints[1] = 2 and $k[2] = 2<br/>
+> <br/>
+> Example 2<br/>
+> Input: @ints = (1, 2, 4, 3, 5), $k = 6<br/>
+> Output: ()<br/>
+> No element in the given array matching the given target.<br/>
+> <br/>
+> Example 3<br/>
+> Input: @ints = (5, 3, 2, 4, 2, 1), $k = 4<br/>
+> Output: (4)<br/>
+> Sorted array: (1, 2, 2, 3, 4, 5)<br/>
+> Target index: (4) as $ints[4] = 4<br/>
+
+I have chosen the straight-forward solution,
+sticking to the instructions very closely:
+`sort` the array, and `grep` the result for indexes where the
+entry matches `$k`.
+
+Not really spectacular...
+
+```perl
+use v5.36;
+
+sub target_index( $ints, $k ) {
+    my @ints = sort $ints->@*;
+    return grep $ints[$_] == $k, 0..$#ints;
+}
+```
+
+## Task 2: Merge Items
+
+> You are given two 2-D array of positive integers, $items1 and $items2 where element is pair of (item_id, item_quantity).<br/>
+> Write a script to return the merged items.<br/>
+> <br/>
+> Example 1<br/>
+> Input: $items1 = [ [1,1], [2,1], [3,2] ]<br/>
+>        $items2 = [ [2,2], [1,3] ]<br/>
+> Output: [ [1,4], [2,3], [3,2] ]<br/>
+> Item id (1) appears 2 times: [1,1] and [1,3]. Merged item now (1,4)<br/>
+> Item id (2) appears 2 times: [2,1] and [2,2]. Merged item now (2,3)<br/>
+> Item id (3) appears 1 time: [3,2]<br/>
+> <br/>
+> Example 2<br/>
+> Input: $items1 = [ [1,2], [2,3], [1,3], [3,2] ]<br/>
+>        $items2 = [ [3,1], [1,3] ]<br/>
+> Output: [ [1,8], [2,3], [3,3] ]<br/>
+> <br/>
+> Example 3<br/>
+> Input: $items1 = [ [1,1], [2,2], [3,3] ]<br/>
+>        $items2 = [ [2,3], [2,4] ]<br/>
+> Output: [ [1,1], [2,9], [3,3] ]<br/>
+
+The first thought is to assign the first set of items to a hash, 
+flattening the entries in the item list, like in
+``` perl
+    my %counts = map $_->@*, $items1->@*;
+```
+But this doesn't work, as this will just overwrite entries like `[1,2]` in
+the second example by `[1,3]`, which appears later in the same list,
+and not add the entries together.
+
+So we really have to do an addition of all the entries of the `$items1` and
+`$items2` lists in a loop.
+
+The data structure that is expected as a result
+is the same as the input structure:
+a reference to an array of ( key, value ) pairs, each represented by a short,
+two-entries anonymous array.
+So we sort the resulting hash by keys to generate that,
+and as we put the result into an anonymous array,
+we can just return the resulting reference.
+
+
+```perl
+use v5.36;
+
+sub merge_items( $items1, $items2 ) {
+    my %counts;
+    $counts{$_->[0]} += $_->[1]
+	for $items1->@*, $items2->@*;
+    return [ map [ $_, $counts{$_} ], sort keys %counts ];
+}
+```
+
+#### **Thank you for the challenge!**
diff --git a/challenge-263/matthias-muth/perl/ch-1.pl b/challenge-263/matthias-muth/perl/ch-1.pl
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+#!/usr/bin/env perl
+#
+#       The Weekly Challenge - Perl & Raku
+#       (https://theweeklychallenge.org)
+#
+#       Challenge 263 Task 1: Target Index
+#
+#       Perl solution by Matthias Muth.
+#
+
+use v5.36;
+
+sub target_index( $ints, $k ) {
+    my @ints = sort $ints->@*;
+    return grep $ints[$_] == $k, 0..$#ints;
+}
+
+use Test2::V0 qw( -no_srand );
+is [ target_index( [1, 5, 3, 2, 4, 2], 2 ) ], [ 1, 2 ],
+    'Example 1: target_index( [1, 5, 3, 2, 4, 2], 2 ) == (1, 2)';
+is [ target_index( [1, 2, 4, 3, 5], 6 ) ], [  ],
+    'Example 2: target_index( [1, 2, 4, 3, 5], 6 ) == ()';
+is [ target_index( [5, 3, 2, 4, 2, 1], 4 ) ], [ 4 ],
+    'Example 3: target_index( [5, 3, 2, 4, 2, 1], 4 ) == 4';
+done_testing;
diff --git a/challenge-263/matthias-muth/perl/ch-2.pl b/challenge-263/matthias-muth/perl/ch-2.pl
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+#!/usr/bin/env perl
+#
+#       The Weekly Challenge - Perl & Raku
+#       (https://theweeklychallenge.org)
+#
+#       Challenge 263 Task 2: Merge Items
+#
+#       Perl solution by Matthias Muth.
+#
+
+use v5.36;
+use Data::Dump qw( pp );
+
+sub merge_items( $items1, $items2 ) {
+    #my %counts;
+    my %counts = map $_->@*, $items1->@*;
+    say pp \%counts;
+    $counts{$_->[0]} += $_->[1]
+	for $items1->@*, $items2->@*;
+    return [ map [ $_, $counts{$_} ], sort keys %counts ];
+
+}
+
+use Test2::V0 qw( -no_srand );
+is merge_items( [[1, 1], [2, 1], [3, 2]], [[2, 2], [1, 3]] ), [[1, 4], [2, 3], [3, 2]],
+    'Example 1: merge_items( [[1, 1], [2, 1], [3, 2]], [[2, 2], [1, 3]] ) == [[1, 4], [2, 3], [3, 2]]';
+is merge_items( [[1, 2], [2, 3], [1, 3], [3, 2]], [[3, 1], [1, 3]] ), [[1, 8], [2, 3], [3, 3]],
+    'Example 2: merge_items( [[1, 2], [2, 3], [1, 3], [3, 2]], [[3, 1], [1, 3]] ) == [[1, 8], [2, 3], [3, 3]]';
+is merge_items( [[1, 1], [2, 2], [3, 3]], [[2, 3], [2, 4]] ), [[1, 1], [2, 9], [3, 3]],
+    'Example 3: merge_items( [[1, 1], [2, 2], [3, 3]], [[2, 3], [2, 4]] ) == [[1, 1], [2, 9], [3, 3]]';
+done_testing;
diff --git a/challenge-263/matthias-muth/perl/challenge-263.txt b/challenge-263/matthias-muth/perl/challenge-263.txt
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+The Weekly Challenge - 263
+Monday, Apr 1, 2024
+
+
+Task 1: Target Index
+Submitted by: Mohammad Sajid Anwar
+
+You are given an array of integers, @ints and a target element $k.
+Write a script to return the list of indices in the sorted array where the element is same as the given target element.
+Example 1
+
+Input: @ints = (1, 5, 3, 2, 4, 2), $k = 2
+Output: (1, 2)
+
+Sorted array: (1, 2, 2, 3, 4, 5)
+Target indices: (1, 2) as $ints[1] = 2 and $ints[2] = 2
+
+Example 2
+
+Input: @ints = (1, 2, 4, 3, 5), $k = 6
+Output: ()
+
+No element in the given array matching the given target.
+
+Example 3
+
+Input: @ints = (5, 3, 2, 4, 2, 1), $k = 4
+Output: (4)
+
+Sorted array: (1, 2, 2, 3, 4, 5)
+Target index: (4) as $ints[4] = 4
+
+
+Task 2: Merge Items
+Submitted by: Mohammad Sajid Anwar
+
+You are given two 2-D array of positive integers, $items1 and $items2 where element is pair of (item_id, item_quantity).
+Write a script to return the merged items.
+Example 1
+
+Input: $items1 = [ [1,1], [2,1], [3,2] ]
+       $items2 = [ [2,2], [1,3] ]
+Output: [ [1,4], [2,3], [3,2] ]
+
+Item id (1) appears 2 times: [1,1] and [1,3]. Merged item now (1,4)
+Item id (2) appears 2 times: [2,1] and [2,2]. Merged item now (2,3)
+Item id (3) appears 1 time: [3,2]
+
+Example 2
+
+Input: $items1 = [ [1,2], [2,3], [1,3], [3,2] ]
+       $items2 = [ [3,1], [1,3] ]
+Output: [ [1,8], [2,3], [3,3] ]
+
+Example 3
+
+Input: $items1 = [ [1,1], [2,2], [3,3] ]
+       $items2 = [ [2,3], [2,4] ]
+Output: [ [1,1], [2,9], [3,3] ]
+
+
+Last date to submit the solution 23:59 (UK Time) Sunday 7th April 2024.