Solve 2024-05

2024/05/index.ts

@@ -0,0 +1,53 @@
+import { getMiddleElement, sumArray } from '../../utils/array.ts';
+
+export function solveFirst(input: string): number {
+  const { order, rows } = parseInput(input);
+
+  const filteredRows = rows.filter((r) => isInOrder(r, order));
+
+  const middles = filteredRows.map((r) => r[Math.floor(r.length / 2)]);
+
+  return sumArray(middles);
+}
+
+function parseInput(input: string) {
+  const order = Array.from(
+    input.matchAll(/^(\d*)\|(\d*)$/gm),
+    (m) => [Number(m[1]), Number(m[2])] as [number, number]
+  );
+  const rows = Array.from(input.matchAll(/^(\d+,?)+$/gm), (m) =>
+    m[0].split(',').map((n) => Number(n))
+  );
+  return { order, rows };
+}
+
+function isInOrder(numbers: number[], order: [number, number][]) {
+  return numbers.every((number, index) => {
+    return order
+      .filter((o) => o[0] === number)
+      .every((o) => numbers.indexOf(o[1]) > index || numbers.indexOf(o[1]) < 0);
+  });
+}
+
+export function solveSecond(input: string): number {
+  const { order, rows } = parseInput(input);
+
+  const filteredRows = rows.filter((r) => !isInOrder(r, order));
+
+  const sorted = filteredRows.map((r) =>
+    r.toSorted((a, b) => {
+      // Find [a,b] meaning a should be before b = -1
+      return order.findIndex((o) => o[0] === a && o[1] === b) >= 0
+        ? -1
+        : // Find [b,a] meaning a should be after b = 1
+          order.findIndex((o) => o[1] === a && o[0] === b) >= 0
+          ? 1
+          : // No order specified, just ignore = 0
+            0;
+    })
+  );
+
+  const middles = sorted.map(getMiddleElement);
+
+  return sumArray(middles);
+}