From b744356b9515b100e6038dc131159feeb255278f Mon Sep 17 00:00:00 2001
From: Lubos Kolouch <lubos@kolouch.net>
Date: Tue, 11 Feb 2025 15:11:02 +0100
Subject: Challenge 308 LK Perl Python

---
 challenge-308/lubos-kolouch/perl/ch-1.pl   | 76 ++++++++++++++++++++++++
 challenge-308/lubos-kolouch/perl/ch-2.pl   | 93 ++++++++++++++++++++++++++++++
 challenge-308/lubos-kolouch/python/ch-1.py | 54 +++++++++++++++++
 challenge-308/lubos-kolouch/python/ch-2.py | 68 ++++++++++++++++++++++
 4 files changed, 291 insertions(+)
 create mode 100644 challenge-308/lubos-kolouch/perl/ch-1.pl
 create mode 100644 challenge-308/lubos-kolouch/perl/ch-2.pl
 create mode 100644 challenge-308/lubos-kolouch/python/ch-1.py
 create mode 100644 challenge-308/lubos-kolouch/python/ch-2.py

diff --git a/challenge-308/lubos-kolouch/perl/ch-1.pl b/challenge-308/lubos-kolouch/perl/ch-1.pl
new file mode 100644
index 0000000000..46fe045bc0
--- /dev/null
+++ b/challenge-308/lubos-kolouch/perl/ch-1.pl
@@ -0,0 +1,76 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+use Test::More tests => 3;
+
+=pod
+
+=head1 Task 1: Count Common
+
+Given two array of strings, @str1 and @str2,
+return the count of common strings in both arrays.
+
+Examples:
+  Input: @str1 = ("perl", "weekly", "challenge")
+         @str2 = ("raku", "weekly", "challenge")
+  Output: 2
+
+  Input: @str1 = ("perl", "raku", "python")
+         @str2 = ("python", "java")
+  Output: 1
+
+  Input: @str1 = ("guest", "contribution")
+         @str2 = ("fun", "weekly", "challenge")
+  Output: 0
+
+=cut
+
+# typedef: In this context, our inputs are array refs of strings (ArrayRef[Str]).
+
+sub count_common {
+    my ( $arr1_ref, $arr2_ref ) = @_;
+
+# Validate that each input is an array reference of strings (not enforced, but assumed)
+
+    # Use a hash to track the unique strings in the first array.
+    my %common;
+    foreach my $elem (@$arr1_ref) {
+        $common{$elem} = 1;
+    }
+
+    my $count = 0;
+
+    # For every element in the second array, check for existence in %common
+    foreach my $elem (@$arr2_ref) {
+        if ( exists $common{$elem} ) {
+            $count++;
+
+            # Remove to prevent duplicate counting if repeated in second array.
+            delete $common{$elem};
+        }
+    }
+    return $count;
+}
+
+# Unit tests
+is(
+    count_common(
+        [ "perl", "weekly", "challenge" ],
+        [ "raku", "weekly", "challenge" ]
+    ),
+    2,
+    "Example 1"
+) or diag "Failed for Example 1";
+
+is( count_common( [ "perl", "raku", "python" ], [ "python", "java" ] ),
+    1, "Example 2" )
+  or diag "Failed for Example 2";
+
+is(
+    count_common(
+        [ "guest", "contribution" ],
+        [ "fun",   "weekly", "challenge" ]
+    ),
+    0,
+    "Example 3"
+) or diag "Failed for Example 3";
diff --git a/challenge-308/lubos-kolouch/perl/ch-2.pl b/challenge-308/lubos-kolouch/perl/ch-2.pl
new file mode 100644
index 0000000000..e6f208b6a3
--- /dev/null
+++ b/challenge-308/lubos-kolouch/perl/ch-2.pl
@@ -0,0 +1,93 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+use feature 'say';
+use Test::More tests => 3;
+
+=pod
+
+=head1 NAME
+
+xor_decode.pl - Task 2: Decode XOR
+
+=head1 DESCRIPTION
+
+This script decodes an original array from an encoded array based on the following encoding:
+
+    encoded[i] = original[i] XOR original[i+1]
+
+Given the encoded array and an initial value (the first element of original),
+the original array is restored.
+
+=head1 FUNCTIONS
+
+=head2 decode_xor
+
+    decode_xor($encoded_array_ref, $initial) => $original_array_ref
+
+Decodes the original array from an encoded array reference and an initial value.
+
+=over 4
+
+=item * C<$encoded_array_ref>: Reference to an array of integers (EncodedArray)
+
+=item * C<$initial>: An integer representing the first element of the original array
+
+=back
+
+Returns a reference to the decoded original array.
+
+=head1 TYPEDEFS
+
+=over
+
+=item * EncodedArray - ArrayRef[Integer]
+
+=item * OriginalArray - ArrayRef[Integer]
+
+=back
+
+=cut
+
+sub decode_xor {
+    my ( $encoded_ref, $initial ) = @_;
+
+    # Ensure $encoded_ref is an array reference
+    die "First argument must be an array reference"
+      unless ref $encoded_ref eq 'ARRAY';
+
+    my @original = ($initial);
+    for my $enc (@$encoded_ref) {
+
+        # Bitwise XOR operator in Perl is "^"
+        push @original, $original[-1] ^ $enc;
+    }
+    return \@original;
+}
+
+# Unit tests
+
+# Example 1:
+my $encoded_ref1  = [ 1, 2, 3 ];
+my $initial1      = 1;
+my $expected_ref1 = [ 1, 0, 2, 1 ];
+is_deeply( decode_xor( $encoded_ref1, $initial1 ),
+    $expected_ref1, 'Example 1 decode' );
+
+# Example 2:
+my $encoded_ref2  = [ 6, 2, 7, 3 ];
+my $initial2      = 4;
+my $expected_ref2 = [ 4, 2, 0, 7, 4 ];
+is_deeply( decode_xor( $encoded_ref2, $initial2 ),
+    $expected_ref2, 'Example 2 decode' );
+
+# Test with an empty encoded array:
+my $encoded_ref3  = [];
+my $initial3      = 10;
+my $expected_ref3 = [10];
+is_deeply( decode_xor( $encoded_ref3, $initial3 ),
+    $expected_ref3, 'Empty encoded decode' );
+
+done_testing();
+
+1;
diff --git a/challenge-308/lubos-kolouch/python/ch-1.py b/challenge-308/lubos-kolouch/python/ch-1.py
new file mode 100644
index 0000000000..227a3fa942
--- /dev/null
+++ b/challenge-308/lubos-kolouch/python/ch-1.py
@@ -0,0 +1,54 @@
+#!/usr/bin/env python3
+"""
+Task 1: Count Common
+
+Given two arrays of strings, str1 and str2,
+return the count of common strings in both arrays.
+
+Examples:
+  Input: str1 = ["perl", "weekly", "challenge"]
+         str2 = ["raku", "weekly", "challenge"]
+  Output: 2
+
+  Input: str1 = ["perl", "raku", "python"]
+         str2 = ["python", "java"]
+  Output: 1
+
+  Input: str1 = ["guest", "contribution"]
+         str2 = ["fun", "weekly", "challenge"]
+  Output: 0
+
+"""
+
+import unittest
+
+# typedef: Define a type alias for list of strings.
+StrList = list[str]
+
+
+def count_common(str1: StrList, str2: StrList) -> int:
+    """
+    Count the number of common strings between two lists.
+    """
+    return len(set(str1).intersection(str2))
+
+
+class TestCountCommon(unittest.TestCase):
+
+    def test_example1(self):
+        self.assertEqual(
+            count_common(["perl", "weekly", "challenge"],
+                         ["raku", "weekly", "challenge"]), 2)
+
+    def test_example2(self):
+        self.assertEqual(
+            count_common(["perl", "raku", "python"], ["python", "java"]), 1)
+
+    def test_example3(self):
+        self.assertEqual(
+            count_common(["guest", "contribution"],
+                         ["fun", "weekly", "challenge"]), 0)
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/challenge-308/lubos-kolouch/python/ch-2.py b/challenge-308/lubos-kolouch/python/ch-2.py
new file mode 100644
index 0000000000..11b038dc85
--- /dev/null
+++ b/challenge-308/lubos-kolouch/python/ch-2.py
@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+"""
+Module: xor_decode
+Task 2: Decode XOR
+
+Given an encoded array where each element is the XOR of consecutive elements from the original array,
+this module provides a function to restore the original array from the encoded array and an initial value.
+
+The encoding is defined as:
+    encoded[i] = original[i] XOR original[i+1]
+
+Example:
+    Input:  encoded = [1, 2, 3], initial = 1
+    Output: [1, 0, 2, 1]
+"""
+
+from typing import NewType
+import unittest
+
+# Type definitions for clarity
+EncodedArray = NewType("EncodedArray", list[int])  # EncodedArray: list of int
+OriginalArray = list[int]  # OriginalArray: list of int
+
+
+def decode_xor(encoded: list[int], initial: int) -> OriginalArray:
+    """
+    Decode the original array from an encoded array and an initial value.
+
+    The encoded array is defined such that:
+        encoded[i] = original[i] XOR original[i+1]
+
+    Args:
+        encoded (List[int]): A list of integers representing the XOR encoded array.
+        initial (int): The first element of the original array.
+
+    Returns:
+        List[int]: The decoded original array.
+
+    Examples:
+        >>> decode_xor([1, 2, 3], 1)
+        [1, 0, 2, 1]
+    """
+    original = [initial]
+    for value in encoded:
+        # The inverse of XOR: original[i+1] = original[i] XOR encoded[i]
+        original.append(original[-1] ^ value)
+    return original
+
+
+# Unit tests
+class TestDecodeXOR(unittest.TestCase):
+    """Unit tests for the decode_xor function."""
+
+    def test_example1(self):
+        """Test with first example."""
+        self.assertEqual(decode_xor([1, 2, 3], 1), [1, 0, 2, 1])
+
+    def test_example2(self):
+        """Test with second example."""
+        self.assertEqual(decode_xor([6, 2, 7, 3], 4), [4, 2, 0, 7, 4])
+
+    def test_empty_encoded(self):
+        """Test with an empty encoded array."""
+        self.assertEqual(decode_xor([], 10), [10])
+
+
+if __name__ == '__main__':
+    unittest.main()
-- 
cgit