带你读《现代TypeScript高级教程》十八、TS实战之扑克牌排序（4）

export function handRank(
 cardStrings: [string, string, string, string, string]): Hand {
 const cards: Card[] = cardStrings.map((str: string) => ({
   rank: rankToNumber(
     str.substring(0, str.length - 1) as Rank
   ),
   suit: suitToNumber(str.at(-1) as Suit)
 }));
 // We won't use the [0] place in the following arrays
 const countBySuit = new Array(5).fill(0);
 const countByRank = new Array(15).fill(0);
 const countBySet = new Array(5).fill(0);
 cards.forEach((card: Card) => {
   countByRank[card.rank]++;
   countBySuit[card.suit]++;
 });
 countByRank.forEach(
   (count: number) => count && countBySet[count]++
 );
 // count the A also as a 14, for straights
 countByRank[14] = countByRank[1];
 if (countBySet[4] === 1 && countBySet[1] === 1)
   return Hand.FourOfAKind;
 else if (countBySet[3] && countBySet[2] === 1)
   return Hand.FullHouse;
 else if (countBySet[3] && countBySet[1] === 2)
   return Hand.ThreeOfAKind;
 else if (countBySet[2] === 2 && countBySet[1] === 1)
   return Hand.TwoPairs;
 else if (countBySet[2] === 1 && countBySet[1] === 3)
   return Hand.OnePair;
 else if (countBySet[1] === 5) {
   if (countByRank.join('').includes('11111'))
     return !countBySuit.includes(5)
       ? Hand.Straight
       : countByRank.slice(10).join('') === '11111'
       ? Hand.RoyalFlush
       : Hand.StraightFlush;
   else {
     /* !countByRank.join("").includes("11111") */
     return countBySuit.includes(5)
       ? Hand.Flush
       : Hand.HighCard;
   }
 } else {
   throw new Error(
     'Unknown hand! This cannot happen! Bad logic!'
   );
 }}

console.log(handRank(['3♥', '5♦', '8♣', 'A♥', '6♠'])); // 0console.log(handRank(['3♥', '5♦', '8♣', 'A♥', '5♠'])); // 1console.log(handRank(['3♥', '5♦', '3♣', 'A♥', '5♠'])); // 2console.log(handRank(['3♥', '5♦', '8♣', '5♥', '5♠'])); // 3console.log(handRank(['3♥', '2♦', 'A♣', '5♥', '4♠'])); // 4console.log(handRank(['J♥', '10♦', 'A♣', 'Q♥', 'K♠'])); // 4console.log(handRank(['3♥', '4♦', '7♣', '5♥', '6♠'])); // 4console.log(handRank(['3♥', '4♥', '9♥', '5♥', '6♥'])); // 5console.log(handRank(['3♥', '5♦', '3♣', '5♥', '3♠'])); // 6console.log(handRank(['3♥', '3♦', '3♣', '5♥', '3♠'])); // 7console.log(handRank(['3♥', '4♥', '7♥', '5♥', '6♥'])); // 8console.log(handRank(['K♥', 'Q♥', 'A♥', '10♥', 'J♥'])); // 9