Perl Weekly Challenge 104: recursion and picking

One way to let me improve my knowledge about Raku (aka Perl 6) is to implement programs in it. Unluckily, I don’t have any production code to implement in Raku yet (sob!). So, why not try solving the Perl Weekly Challenge tasks?

In the following, the assigned tasks for Challenge 104.

• Task 1
• Task 2

PWC 104 - Task 1

The first task was quite simple: it required to compute a FUSC sequence, that is something that can be computed recusrively. Since Raku allows for parameter value overloading of a function, why not use that?

multi sub fusc( 0 ) { 0 }
multi sub fusc( 1 ) { 1 }
multi sub fusc( $n where { $n > 1 } ) {
    return samewith( ( $n / 2 ).Int ) if $n %% 2;
    return samewith( ( ( $n - 1 ) / 2 ).Int ) + samewith( ( ( $n + 1 ) / 2 ).Int );
}


sub MAIN(){
    "fusc( $_ ) = { fusc( $_ )}".say for 0 .. 10;
}

The idea is to define a fusc function that will have fixed values for 0 and 1 and will recursively call itself by mean of samewith with different arguments. There is the need to add a cast to Int or the recursive call will not be able to find out the correct candidate.

PWC 104 - Task 2

The second task was about a game where the players have to pick 1 or 2 or 3 tokens at the same time, and the one that picks the last token from a group of 12 wins. I’ve implemented it using an array of @tokens from which I remove a random number of tokens at every round, for two players:

sub MAIN() {
    # all tokens are True-selectable
    my @tokens = True xx 12;

    my @players = <Player1 Player2>;

    while ( @tokens.elems > 0 ) {
        for @players -> $player {
            my $how-many = ( 1 .. min( 3, @tokens.elems ) ).pick;
            @tokens.pop for 1 .. $how-many;
            say "$player picks $how-many, remaining { @tokens.elems }";

            if @tokens.elems == 0 && $how-many > 0 {
                "Player $player won!".say && exit;
            }
        }

    }

}
}

At every round the @tokens array is reduced by a random number between the maximum of 3 and the number of remaining tokens. The player that picks the last token in that round wins and terminates the whole application.