Solve 2023 day 7 part 1

2023/Day7/javascript/solve.js

@@ -0,0 +1,92 @@
+const fs = require("node:fs");
+const path = require("node:path");
+
+const input = fs
+  .readFileSync(path.join(__dirname, "../input.txt"), "utf8")
+  .split("\n")
+  .filter((line) => line !== "");
+
+const RANKS = "0123456789TJQKA";
+
+const getValue = (hand) => {
+  if (fiveOfAKind(hand)) return 6;
+  if (fourOfAKind(hand)) return 5;
+  if (fullHouse(hand)) return 4;
+  if (threeOfAKind(hand)) return 3;
+  if (twoPair(hand)) return 2;
+  if (onePair(hand)) return 1;
+  return 0;
+};
+
+const fiveOfAKind = (hand) => {
+  const parsed = group(hand.split(""));
+  return Object.values(parsed).some((rank) => rank.length == 5);
+};
+
+const fourOfAKind = (hand) => {
+  const parsed = group(hand.split(""));
+  return Object.values(parsed).some((rank) => rank.length == 4);
+};
+
+const fullHouse = (hand) => {
+  const parsed = group(hand.split(""));
+  return (
+    Object.values(parsed).some((rank) => rank.length == 3) &&
+    Object.values(parsed).some((rank) => rank.length == 2)
+  );
+};
+
+const threeOfAKind = (hand) => {
+  const parsed = group(hand.split(""));
+  return Object.values(parsed).some((rank) => rank.length == 3);
+};
+
+const twoPair = (hand) => {
+  const parsed = group(hand.split(""));
+  return Object.values(parsed).filter((value) => value.length == 2).length == 2;
+};
+
+const onePair = (hand) => {
+  const parsed = group(hand.split(""));
+  return Object.values(parsed).filter((value) => value.length == 2).length == 1;
+};
+
+const group = (arr) =>
+  arr.reduce((acc, cur) => {
+    const firstLetter = cur[0].toLowerCase();
+    return { ...acc, [firstLetter]: [...(acc[firstLetter] || []), cur] };
+  }, {});
+
+const part1 = (lines) => {
+  const ranked = [[], [], [], [], [], [], []];
+  for (const line of lines) {
+    const [hand, bidStr] = line.split(" ");
+
+    ranked[getValue(hand)].push(line);
+  }
+
+  const sorted = ranked.map((rank) =>
+    rank.sort((a, b) => {
+      for (let i = 0; i < a.length; i++) {
+        if (RANKS.indexOf(a[i]) < RANKS.indexOf(b[i])) {
+          return -1;
+        } else if (RANKS.indexOf(a[i]) > RANKS.indexOf(b[i])) {
+          return 1;
+        }
+      }
+
+      return 0;
+    })
+  );
+
+  return sorted
+    .flat()
+    .map((hand, i) => {
+      const [_, bidStr] = hand.split(" ");
+      const bid = Number.parseInt(bidStr);
+      return bid * (i + 1); // Index starts at 0
+    })
+    .reduce((acc, curr) => acc + curr, 0);
+};
+
+console.log(part1(input));