Task — Zip list

You are given two lists @a and @b of the same size. Create a subroutine sub zip(@a, @b) that merge the two list as shown in the example below.

Examples

Example
Input:  @a = qw/1 2 3/; @b = qw/a b c/;
Output: zip(@a, @b) should return qw/1 a 2 b 3 c/;
        zip(@b, @a) should return qw/a 1 b 2 c 3/;

Analysis

Travelling in New Zealand we noticed that when two lanes of traffic merge into one, the road sign says 'Merge like a zip'. And that's what's needed here.

This could be achieved in a single line, but it would be a rather messy one, hard to understand or maintain. So let's not.

As stated, zip(@a, @b) will create a single array @_ which is the concatenation of @a and @b. Lets' start by splitting that into the two equal length @a and @b. We can then create the desired output as:

push @result, $a[$_], $b[$_] for 0 .. @a - 1;

And that's it.

Try it 

Script

#!/usr/bin/perl

# Peter Campbell Smith - 2022-10-10
# PWC 186 task 1

use v5.28;
use utf8;
use warnings;
binmode(STDOUT, ':utf8');

zip(qw/1 2 3/, qw/a b c/);
zip(qw/c r e t a s e/, qw/o r c - n w r/);

sub zip {
    
    my (@a, @b, $n, @result);
    
    # create output
    $n = @_ / 2;
    @a = @_[0 .. $n - 1];
    @b = @_[$n .. @_ - 1];
    push @result, $a[$_], $b[$_] for 0 .. @a - 1;
    
    # print it
    say qq[\nInput:  (] . join(', ', @a) . qq[), (] . join(', ', @b) . qq[)];
    say qq[Output: (] . join(', ', @result)  . ')';
}

Output

Input:  (1, 2, 3), (a, b, c)
Output: (1, a, 2, b, 3, c)

Input:  (c, r, e, t, a, s, e), (o, r, c, -, n, w, r)
Output: (c, o, r, r, e, c, t, -, a, n, s, w, e, r)