Solution to task 1

1 files changed, 75 insertions, 0 deletions

diff --git a/challenge-208/jo-37/perl/ch-1.pl b/challenge-208/jo-37/perl/ch-1.pl
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+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0;
+use List::UtilsBy 'min_by';
+use experimental 'signatures';
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV == 2;
+usage: $0 [-examples] [-tests] [LIST1 LIST2]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+LIST1 LIST2
+    two lists of comma separated words
+
+EOS
+
+
+### Input and Output
+
+say "(@{[min_ind_sum(map [split /,/, $_], @ARGV)]})";
+
+
+### Implementation
+
+sub min_ind_sum ($x, $y) {
+    # Build key-value pairs from the strings in @$y and their index
+    # position.
+    my %hy;
+    @hy{@$y} = (0 .. $#$y);
+
+    # Build key-value pairs from the strings in @$x and their index sum
+    # within both arrays.
+    my %hx;
+    @hx{@$x} = do {
+        # Add the index positions in @$x and @$y for common strings.
+        # Strings in @$x that are missing in @$y produce infinity.
+        my $i = 0;
+        map $i++ + ($_ // 'inf'), delete @hy{@$x};
+    };
+
+    # Select all elements from @$x having a finite minimum index sum.
+    min_by {$hx{$_}} grep $hx{$_} < 'inf', @$x;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        is [min_ind_sum(["Perl", "Raku", "Love"], ["Raku", "Perl", "Hate"])],
+            ["Perl", "Raku"], 'example 1';
+        is [min_ind_sum(["A", "B", "C"], ["D", "E", "F"])],
+            [], 'example 2';
+        is [min_ind_sum(["A", "B", "C"], ["C", "A", "B"])],
+            ["A"], 'example 3';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+	}
+
+    done_testing;
+    exit;
+}