Perl 6 示例二十一点！
作者：David Whipp
在“二十一点！”游戏中，参赛者必须编写一个脚本，用于发牌并玩一局二十一点（也称为黑杰克）。
比赛场景
作为高级组的决赛项目，您必须编写一个脚本，该脚本可以发牌并玩一局二十一点（也称为黑杰克）。在本项目中，我们将玩一个简化版的二十一点，其规则如下：
不涉及下注。（抱歉，也许明年会加入。）
所有 A 都计为 11 点。是的，我们知道：在标准的二十一点中，A 可以计为 1 点或 11 点。但是，在项目 10 中，A 只能计为 11 点。（我们不想让这个项目太复杂。）
好吧，如果您愿意，可以让 A 计为 1 点或 11 点。但除非您想这样做，否则不必这样做。
所有花牌（国王、皇后、杰克）都计为 10 点。
所有其他牌都等于其面值：黑桃 3 计为 3 点，方块 7 计为 7 点，等等。
平局（推）算庄家赢。假设，在一局结束时，玩家有 18 点，庄家也有 18 点。在这种情况下，庄家被宣布为获胜者。
您的脚本应该首先“洗牌”一副标准的扑克牌，然后给玩家发两张牌，再给庄家发两张牌。（不知道“一副标准的扑克牌”有哪些牌？请点击此处了解更多信息。）与正规的二十一点一样，发给玩家的两张牌应该是“面朝上”的；也就是说，两张牌都应该亮出来。
Your cards: Seven of Spades Eight of Spades
相反，庄家的两张牌只有一张应该亮出来。
Dealer's cards: Ace of Hearts
注意：请注意，我们是用名称来指定纸牌的。不要只列出纸牌的值，像这样：
7 8
这将导致您的脚本失败。在列出纸牌时要具体。
同样，按照标准的二十一点规则，玩家应该可以选择要牌（玩发给他的两张牌）或停牌（不再要牌）。换句话说：
Stay (s) or hit (h) ?
如果玩家选择“要牌”，那么应该再给他发一张牌。如果三张牌的总和超过 21，那么玩家自动输掉。
Stay (s) or hit (h) ?h Seven of Spades Eight of Spades Seven of Diamonds Over 21. Sorry, you lose.
如果总和是 20 或更少，那么玩家将有另一次机会选择要牌或停牌。（如果总和是 21，则玩家获胜。）一旦玩家选择停牌，庄家（计算机）就会检查自己的点数是否超过玩家。例如，假设玩家有黑桃 7 和黑桃 8；这意味着玩家有 15 点。现在假设庄家有红心 A 和方块 6。这意味着庄家有 17 点（11 + 6），这也意味着庄家自动获胜。
现在，假设玩家有 16 点，庄家有 13 点。在这种情况下，必须再给庄家发一张牌。让我们来看看下一张牌的一些可能性：
庄家得到一张 2，使庄家有 15 点。这比玩家的 16 点少，所以庄家必须继续要牌。
庄家得到一张 9，使他有 22 点。22 大于 21，所以庄家输了。
庄家得到一张 3，使庄家和玩家都有 16 点。因为平局算庄家赢，所以庄家自动获胜。
一局完整的牌局可能像这样进行：
Your cards: King of Hearts Seven of Hearts Dealer's cards: Nine of Hearts Stay (s) or hit (h)?s You have 17. Dealer's cards: Nine of Hearts Seven of Diamonds Dealers' cards: Nine of Hearts Seven of Diamonds Five of Diamonds The dealer has 21. Sorry, you lose.
看到了吗？这应该不会太难，尤其是对于那些已经完成了前九个项目的人来说。
use v6;
sub MAIN(Bool :$computer-player = False) {
my $player_is_human = not $computer-player;
my @values = (
ace => 1|11,
two => 2,
three => 3,
four => 4,
five => 5,
six => 6,
seven => 7,
eight => 8,
nine => 9,
ten => 10,
jack => 10,
queen => 10,
king => 10,
);
my @suites = < spades clubs diamonds hearts >;
my @deck = ( @values X @suites ).flat.map: {
my ($name, $value) = $^a.kv;
$name ~= " of $^b";
$name => $value
};
my @cards = $computer-player ?? default-cards() !! @deck.pick( @deck.elems );
my @dealer;
my @player;
@dealer.push( @cards.shift );
@player.push( @cards.shift );
@dealer.push( @cards.shift );
say "DEALER:";
say @dealer[0].key;
say "";
say "PLAYER:";
.key.say for @player;
my $player_value = [+] @player.map: { .value };
loop {
my $card = @cards.shift;
@player.push( $card );
say $card.key;
$player_value += $card.value;
say "current value is { $player_value.perl }";
if $player_value == 21 {
say "congratulations, you win!";
exit 0;
}
elsif $player_value < 21 {
say "hit (h) or stay (s)";
my $choice;
if ($player_is_human) {
loop {
$choice = lc $*IN.get;
last if $choice eq "h" | "s";
say "invalid entry: 'h' or 's'";
}
}
else {
$choice = $player_value < 16 ?? "hit" !! "stay";
}
say $choice;
last if $choice ~~ /s/;
}
else {
say "sorry, you bust!";
exit 0;
}
}
say "";
$player_value = max (4 .. 21).grep: { $_ == $player_value };
say "DEALER:";
.key.say for @dealer;
my $dealer_value = [+] @dealer.map: { .value };
loop {
say "dealer value: {$dealer_value.perl}";
if $dealer_value == any( $player_value ^.. 21) {
say "you lose!";
exit 0;
}
elsif $dealer_value < 21 {
my $card = @cards.shift;
@dealer.push( $card );
say $card.key;
$dealer_value += $card.value;
}
else {
say "dealer bust: you win!";
exit 0;
}
}
}
sub default-cards {
return [
"three of diamonds" => 3,
"five of diamonds" => 5,
"seven of diamonds" => 7,
"ten of diamonds" => 10,
"two of diamonds" => 2,
"jack of spades" => 10,
"five of clubs" => 5,
"five of hearts" => 5,
"eight of diamonds" => 8,
"six of spades" => 6,
"five of spades" => 5,
"king of hearts" => 10,
"nine of diamonds" => 9,
"two of hearts" => 2,
"king of clubs" => 10,
"eight of clubs" => 8,
"two of spades" => 2,
"ace of hearts" => any(1, 11),
"nine of hearts" => 9,
"eight of spades" => 8,
"jack of diamonds" => 10,
"jack of hearts" => 10,
"nine of clubs" => 9,
"ten of hearts" => 10,
"eight of hearts" => 8,
"king of spades" => 10,
"ace of spades" => any(1, 11),
"queen of hearts" => 10,
"nine of spades" => 9,
"two of clubs" => 2,
"queen of diamonds" => 10,
"three of spades" => 3,
"queen of clubs" => 10,
"three of clubs" => 3,
"ten of spades" => 10,
"ace of clubs" => any(1, 11),
"ace of diamonds" => any(1, 11),
"four of hearts" => 4,
"six of clubs" => 6,
"ten of clubs" => 10,
"seven of hearts" => 7,
"king of diamonds" => 10,
"four of diamonds" => 4,
"seven of spades" => 7,
"queen of spades" => 10,
"four of spades" => 4,
"six of hearts" => 6,
"four of clubs" => 4,
"seven of clubs" => 7,
"six of diamonds" => 6,
"three of hearts" => 3,
"jack of clubs" => 10]<>;
}