Solve 2024-13

2024/13/2024-13.run.xml

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+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="2024-13" type="BunRunConfiguration">
+    <option name="program" value="2024/13/run.ts" />
+    <option name="workingDirectory" value="$PROJECT_DIR$" />
+    <method v="2" />
+  </configuration>
+</component>

2024/13/index.test.ts

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+import { describe, expect, it } from 'bun:test';
+import { solveFirst, solveSecond } from './index.ts';
+
+describe('2024-13', () => {
+  const testInput = `Button A: X+94, Y+34
+Button B: X+22, Y+67
+Prize: X=8400, Y=5400
+
+Button A: X+26, Y+66
+Button B: X+67, Y+21
+Prize: X=12748, Y=12176
+
+Button A: X+17, Y+86
+Button B: X+84, Y+37
+Prize: X=7870, Y=6450
+
+Button A: X+69, Y+23
+Button B: X+27, Y+71
+Prize: X=18641, Y=10279`;
+  it('first', () => {
+    expect(solveFirst(testInput)).toBe(480);
+  });
+  it('second', () => {
+    expect(solveSecond(testInput)).toBe(875318608908);
+  });
+});

2024/13/index.ts

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+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);
+}

2024/13/run.ts

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+import { join } from 'path';
+import { solveFirst, solveSecond } from './index.ts';
+
+const input = await Bun.file(join(__dirname, 'input.txt')).text();
+
+const firstAnswer = solveFirst(input);
+
+console.log(firstAnswer);
+
+const secondAnswer = solveSecond(input);
+
+console.log(secondAnswer);