day 23 (#21)

23/final_input.txt

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+952438716

23/readme.md

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+# Day 23: Crap Cups
+https://adventofcode.com/2020/day/23

23/src/23.ts

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+class ListNode<T>
+{
+    public next!: ListNode<T>;
+
+    constructor(
+        public readonly data: T
+    ) {
+    }
+}
+
+class LinkedList<T>
+{
+    constructor(
+        public head: ListNode<T>
+    ) {
+    }
+
+    public toList(limitFromHead=Infinity): T[]
+    {
+        const list = [];
+        let head: ListNode<T>["next"] = this.head;
+
+        let i = 0;
+        do {
+            list.push(head!.data);
+            head = head!.next;
+            i++;
+        } while(head !== this.head && i < limitFromHead);
+
+        return list;
+    }
+}
+type LinkedMapList<T> = Map<T, ListNode<T>>;
+
+function playCrabGame(allCupsNumbers: number[], totalRounds: number, minCupLabel: number, maxCupLabel: number): ListNode<number>
+{
+    const list = new LinkedList(new ListNode(allCupsNumbers[0]));
+    const map: LinkedMapList<number> = new Map([[list.head.data, list.head]]);
+    let prev = list.head;
+    for (let i = 1; i < allCupsNumbers.length; i++) {
+        const node = new ListNode(allCupsNumbers[i]);
+        map.set(allCupsNumbers[i], node);
+
+        prev.next = node;
+        prev = node;
+    }
+    // circular linked list
+    prev.next = list.head!;
+
+    let currentHead = list.head;
+
+    for (let round = 0; round < totalRounds; round++) {
+        //console.log(`\n-- move ${round + 1} --`);
+        //console.log(`cups: ${list.toList().map(n => n === currentHead.data ? `(${n})` : n).join(" ")}`);
+
+        const pickUpNodesStart = currentHead.next;
+        const pickUpNodesEnd = currentHead.next.next.next;
+        const pickUp = new LinkedList(currentHead.next).toList(3);
+        currentHead.next = currentHead.next.next.next.next;
+        let destination = currentHead.data - 1;
+        while (pickUp.indexOf(destination) > -1 || destination < minCupLabel) {
+            destination--;
+            if (destination < minCupLabel) {
+                destination = maxCupLabel;
+            }
+        }
+
+        //console.log(`pick up: ${pickUp.join(", ")}`);
+        //console.log(`destination: ${destination}`);
+
+        if (!map.has(destination)) {
+            console.log(`destination ${destination} not found in map: ${[...map.keys()]}`);
+            throw 'BUG';
+        }
+
+        const destinationNode = map.get(destination)!;
+        pickUpNodesEnd.next = destinationNode.next;
+        destinationNode.next = pickUpNodesStart;
+
+        currentHead = currentHead.next;
+    }
+
+    //console.log(`-- final --`);
+    //console.log(`cups: ${list.toList().map((c, i) => i === currentHead.data ? `(${c})` : c).join(" ")}`);
+
+    return map.get(1)!;
+}
+
+export function countPart1(allCupsNumbers: number[], totalRounds: number): number
+{
+    const gameResult = playCrabGame(
+        allCupsNumbers,
+        totalRounds,
+        Math.min.apply(undefined, allCupsNumbers),
+        Math.max.apply(undefined, allCupsNumbers)
+    );
+
+    return Number(new LinkedList<number>(gameResult.next).toList(allCupsNumbers.length - 1).join(""));
+}
+
+export function countPart2(input: number[]): number
+{
+    const max = Math.max.apply(undefined, input);
+    const allCupNumbers = [...input, ...Array.from({length: 1e6-max}, (_, i) => max + 1 + i)];
+
+    const gameResult = playCrabGame(allCupNumbers, 1e7, Math.min.apply(undefined, input), 1e6);
+
+    return gameResult.next.data * gameResult.next.next.data;
+}

23/tests/23.test.ts

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+import {assertStrictEquals} from "../../deps.ts";
+import {countPart1, countPart2} from "../src/23.ts";
+
+Deno.test("Crab Cups: Example test from introduction (Part one)", () => {
+  const input = (
+      "389125467"
+  ).split("").map(Number);
+  const expectedOutput = 92658374;
+
+  assertStrictEquals(countPart1(input, 10), expectedOutput);
+});
+
+Deno.test("Crab Cups: Final test (Part one)", () => {
+  const input = (
+      Deno.readTextFileSync("23/final_input.txt").trimEnd()
+  ).split("").map(Number);
+
+  const expectedOutput = 97342568;
+
+  assertStrictEquals(countPart1(input, 100), expectedOutput);
+});
+
+Deno.test("Crab Cups: Example test from introduction (Part two)", () => {
+  const input = (
+      "389125467"
+  ).split("").map(Number);
+
+  const expectedOutput = 149245887792;
+
+  assertStrictEquals(countPart2(input), expectedOutput);
+});
+
+Deno.test("Crab Cups: Final test (Part two)", () => {
+  const input = (
+      Deno.readTextFileSync("23/final_input.txt").trimEnd()
+  ).split("").map(Number);
+
+  const expectedOutput = 902208073192;
+
+  assertStrictEquals(countPart2(input), expectedOutput);
+});