RogerBW's Blog

I’ve been doing the Weekly Challenges. The latest involved poking about with lists. (Note that this ends today.)

Task 1: Equal List

You are given two arrays of strings.

Write a script to return true if the two given array represent the same strings otherwise false.

In other words, concatenate the arrays into individual strings. Which is quite straightforward in most languages; here in Rust:

fn equallist(a: Vec<&str>, b: Vec<&str>) -> bool {
    a.join("") == b.join("")
}

Task 2: List Division

You are given a list and a non-negative integer.

Write a script to divide the given list into given non-negative integer equal parts. Return -1 if the integer is more than the size of the list.

I replaced the "-1" for an invalid answer with an empty list to allow type consistency.

In Perl:

sub listdivision($a, $n) {

Get the number of items available, and fail if there are too many parts wanted.

  my $al = scalar @{$a};
  if ($n > $al) {
    return [];
  }

Work out an overall division size, stick copies of it in an array, and increment the earlier ones as needed.

  my @divsize = (int ($al / $n)) x $n;
  foreach my $i (0 .. ($al % $n) - 1) {
    $divsize[$i] += 1;
  }

Then take successive slices off the list. (One could do this destructively with splice but I kept a rolling counter instead.)

  my @out;
  my $x = 0;
  my @a = @{$a};
  foreach my $s (@divsize) {
    my @r = @a[$x .. $x + $s - 1];
    push @out, \@r;
    $x += $s;
  }
  \@out;
}

Full code on codeberg.