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bacek (8813)

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Journal of bacek (8813)

Wednesday December 24, 2008
02:31 AM

Scripting Games, part 3

Next one: find winner of skater contest.

        # Calculate score for single result
        sub calculate_score(@scores) {
                # Sort scores
                my @sorted = sort @scores;
                # Drop highest and lowest
                shift @sorted;
                pop @sorted;
                # Calculate final score
                ([+] @sorted)/ +@sorted;

        # Parse line in form "Ken Myer,55,66,76,67,59,70,54", and return (score, name)
        sub parse_line($line) {
                my @parts = $line.split(',');
                reverse(shift @parts, calculate_score(@parts));

        # Main cycle. Read file, parse lines, build mapping score=>name
        my $fh = open('skaters.txt') or die;
        my %results = map &parse_line, =$fh;

        # Get 3 top results
        my @top = %results.keys.sort.reverse[0..2];
        # And show them
        say %results{$_}, ': ', $_ for @top;

I don't know what to say. Solution is straight forward.

02:01 AM

Scripting Games, part 2

Beginner's events are way too easy. Let's take a look at "advanced".

        # First thing first: build letters-to-digits map
        my $pos = 2;
        my %l2d;
        map { %l2d{$^a} = $pos; %l2d{$^b} = $pos; %l2d{$^c} = $pos++ }, 'a'..'p', 'r'..'y';

        # Calculate number representation of word
        sub read_word($word) {
        # join digit for given letters
                [~] map { %l2d{ lc $^a } }, $word.split('');

        # Read wordlist and returns hash (number => word).
        # Also skips all non-7 chars words
        sub read_wordlist($filename) {
                my $fh = open($filename) or die;
                map { read_word($^a) => $^a }, grep { $^a.chars == 7 }, =$fh;

        # Read wordlist file.
        my %words = read_wordlist('wordlist.txt');

        # And say word corresponded to number.
        for =$*IN {
                say uc %words{$_};

Funny note: there is no 'scripts' in wordlist.txt :)

01:11 AM

First post.


In response to Pm's "Scripting games in Perl6" I've decided to implement some of them in Perl6.

Let's start with easiest "2008: Beginners Event 1"

Task is to calculate number of different pairs of cards.

    sub fact($n) {
            $n <= 1 ?? 1 !! $n*fact($n-1);

    sub calculate_pairs(@pairs) {
            my %h;
            # Calculate number of distinct cards.
            ++%h{$_} for @pairs;
            # Sum of C^N_2
            [+] map { int(fact($^a) / 2) }, %h.values;

Trivial mathematical solution: number of different pairs for given amount of cards is C^n_2. So, I group cards, calculate number of combinations in different group and sum them.

Little trick: if number of cards in group equals to 1 than int(...) will return 0.

Update: masak++ for pointing to strange reaction on <=