solve 22a

Author: robinpokorny

day22.test.ts

@@ -0,0 +1,125 @@
+/* === TYPES === */
+
+/* === PREPARE INPUT === */
+
+export const prepareInput = ([input]: TemplateStringsArray) =>
+  input
+    .split("\n\n")
+    .map((block) => block.split("\n"))
+    .map<number[]>(([_player, ...deck]) => deck.map(Number)) as [
+    number[],
+    number[]
+  ];
+
+/* === UTILS === */
+const isEmpty = (arr: unknown[]): boolean => arr.length === 0;
+
+const getScore = (arr: number[]): number =>
+  [...arr]
+    .reverse()
+    .map((n, i) => n * (i + 1))
+    .reduce((a, b) => a + b, 0);
+
+/* === IMPLEMENTATION === */
+const combat = ([deck1, deck2]: [number[], number[]]): [number[], number[]] => {
+  if (isEmpty(deck1) || isEmpty(deck2)) return [deck1, deck2];
+
+  const [top1, ...rest1] = deck1;
+  const [top2, ...rest2] = deck2;
+
+  if (top1 > top2) {
+    return combat([[...rest1, top1, top2], rest2]);
+  } else {
+    return combat([rest1, [...rest2, top2, top1]]);
+  }
+};
+
+/* === TESTS === */
+
+test("Day 22a - test", () => {
+  const [deck1, deck2] = combat(testInput);
+
+  expect(deck2).toEqual([3, 2, 10, 6, 8, 5, 9, 4, 7, 1]);
+
+  expect(getScore(deck1) + getScore(deck2)).toBe(306);
+});
+
+test("Day 22a - prod", () => {
+  const [deck1, deck2] = combat(prodInput);
+
+  expect(getScore(deck1) + getScore(deck2)).toBe(31629);
+});
+
+test.skip("Day 22b - test", () => {});
+
+test.skip("Day 22b - prod", () => {});
+
+/* === INPUTS === */
+
+const testInput = prepareInput`Player 1:
+9
+2
+6
+3
+1
+
+Player 2:
+5
+8
+4
+7
+10`;
+
+const prodInput = prepareInput`Player 1:
+28
+50
+9
+11
+4
+45
+19
+26
+42
+43
+31
+46
+21
+40
+33
+20
+7
+6
+17
+44
+5
+39
+35
+27
+10
+
+Player 2:
+18
+16
+29
+41
+14
+12
+30
+37
+36
+24
+48
+38
+47
+34
+15
+8
+49
+23
+1
+3
+32
+25
+22
+13
+2`;