Solve 2024-13

2024/13/index.ts

@@ -0,0 +1,33 @@
+import { sumArray } from '../../utils/array.ts';
+import { type Coordinate, isInteger } from '../../utils/coordinates.ts';
+
+function findIntersection(input: string, offset: number = 0) {
+  const match = input.matchAll(
+    /^Button A: X\+(\d*), Y\+(\d*)\nButton B: X\+(\d*), Y\+(\d*)\nPrize: X=(\d*), Y=(\d*)$/gm
+  );
+
+  const matches = Array.from(match, (m) => ({
+    a: [m[1], m[2]].map(Number),
+    b: [m[3], m[4]].map(Number),
+    price: [m[5], m[6]].map((n) => Number(n) + offset)
+  }));
+
+  const intersection = matches
+    .map(
+      ({ a: [a1, a2], b: [b1, b2], price: [p1, p2] }) =>
+        [
+          (b1 * -p2 - b2 * -p1) / (a1 * b2 - a2 * b1),
+          (-p1 * a2 - -p2 * a1) / (a1 * b2 - a2 * b1)
+        ] as Coordinate
+    )
+    .filter(isInteger);
+
+  return sumArray(intersection.map(([a, b]) => 3 * a + b));
+}
+
+export function solveFirst(input: string): number {
+  return findIntersection(input);
+}
+export function solveSecond(input: string): number {
+  return findIntersection(input, 10000000000000);
+}