math & informatics teacher
function parse(input, jack = "b") {
return input.split("\n").map((line) => {
const [hand, bid] = line.split(/\s+/);
return {
hand: hand
.replaceAll("A", "e")
.replaceAll("K", "d")
.replaceAll("Q", "c")
.replaceAll("J", jack)
.replaceAll("T", "a"),
bid: Number(bid)
};
});
}
function type1(hand) {
// Find the number of cards of each type
const fTable = new Map();
[...hand].forEach((card) => AOC.addToFreqTable(fTable, card));
const counts = [...fTable.values()];
// Type of hand can largely be determined by testing for the highest frequency in max to min order.
if (counts.includes(5)) {
return 7; // Five of a kind
}
if (counts.includes(4)) {
return 6; // Four of a kind
}
if (counts.length === 2) {
return 5; // Full house
}
if (counts.includes(3)) {
return 4; // Three of a kind
}
if (counts.filter((n) => n === 2).length === 2) {
return 3; // Two pairs
}
if (counts.length === 4) {
return 2; // One pair
}
return 1; // High card
}
function cardSort(type, hand1, hand2) {
const [h1, h2] = [hand1.hand, hand2.hand];
const [t1, t2] = [type(h1), type(h2)];
return t1 === t2 ? (h1 < h2 ? -1 : h1 > h2 ? 1 : 0) : t1 - t2;
}
function part1(input) {
return AOC.sum(
parse(puzzleInput)
.sort(AOC.partial(cardSort, type1))
.map(({ h, bid }, i) => bid * (i + 1))
);
}
function type2(hand) {
// If there are no Jokers in hand, this behaves as part1.
const numJokers = (hand.match(/0/g) || []).length;
if (numJokers === 0) {
return type1(hand);
}
// Find the number of cards of each type excluding Jokers
const handWithoutJokers = hand.replace(/0/g, "");
const fTable = new Map();
[...handWithoutJokers].forEach((card) => AOC.addToFreqTable(fTable, card));
const counts = [...fTable.values()];
// Use the maximum count of any card including use of Jokers to calculate the hand type
switch (Math.max(...counts, 0) + numJokers) {
case 5:
return 7; // Five of a kind
case 4:
return 6; // Four of a kind
case 3:
return counts.length <= 3 - numJokers ? 5 : 4; // Full house or Three of a kind
default:
return 2; // Pair
}
}
function part2(input) {
return AOC.sum(
parse(puzzleInput, "0")
.sort(AOC.partial(cardSort, type2))
.map(({ h, bid }, i) => bid * (i + 1))
);
}
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