# -*- mode: cperl6; -*-

# 2011 Perl 6 Coding Contest
# Edgar Gonzàlez i Pellicer

# Linked lists
module LinkedLists;


# Linked list
class LinkedList is export {
  has $.head;
  has LinkedList $.tail;


  # Elements
  method elems() {
    # Result
    my $result = 0;

    # Follow the list
    my LinkedList $l = self;

    # Next
    while $l.defined {
      # One more
      ++$result;

      # Continue
      $l .= tail;
    }

    # Return
    return $result;
  }


  # To array
  method to-array() {
    # Result
    my @result;

    # Follow the list
    my LinkedList $l = self;

    # Next
    while $l.defined {
      # Add the head
      @result.push($l.head);

      # Continue
      $l .= tail;
    }

    # Return
    return @result;
  }


  # Uniq -c
  method uniq-c() {
    # Result
    my @result;

    # Follow the list
    my LinkedList $l = self;

    # Next
    while $l.defined {
      # Get it
      my $start    = $l.head;
      my $how-many = 1;

      # Continue
      $l .= tail;
      while $l.defined && $l.head == $start {
	$l .= tail;
	++$how-many;
      }

      # Add
      @result.push($start => $how-many);
    }

    # Return
    return @result;
  }
}