Solve 2024-07

2024/07/2024-07.run.xml

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+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="2024-07" type="BunRunConfiguration">
+    <option name="program" value="2024/07/run.ts" />
+    <option name="workingDirectory" value="$PROJECT_DIR$" />
+    <method v="2" />
+  </configuration>
+</component>

2024/07/index.test.ts

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+import { describe, expect, it } from 'bun:test';
+import { solveFirst, solveSecond } from './index.ts';
+
+describe('2024-07', () => {
+  const testInput = `190: 10 19
+3267: 81 40 27
+83: 17 5
+156: 15 6
+7290: 6 8 6 15
+161011: 16 10 13
+192: 17 8 14
+21037: 9 7 18 13
+292: 11 6 16 20`;
+  it('first', () => {
+    expect(solveFirst(testInput)).toBe(3749);
+  });
+  it('second', () => {
+    const secondSolution = solveSecond(testInput);
+    expect(secondSolution).toBe(11387);
+    expect(secondSolution).toBeGreaterThanOrEqual(solveFirst(testInput));
+  });
+});

2024/07/index.ts

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+import { sumBy } from '../../utils/array.ts';
+
+export function solveFirst(input: string): number {
+  const regex = /^(\d*): (.*)$/gm;
+  const match = input.matchAll(regex);
+
+  const rows = Array.from(match, (m) => ({
+    sum: Number(m[1]),
+    digits: m[2].split(' ').map((n) => Number(n))
+  }));
+
+  const possible = rows.filter((r) => {
+    for (let t = 0; t < Math.pow(2, r.digits.length - 1); t++) {
+      const sol = r.digits.reduce((sum, curr, i) =>
+        evalTry(t, i, sum + curr, sum * curr)
+      );
+      if (sol === r.sum) {
+        return true;
+      }
+    }
+    return false;
+  });
+
+  // console.log(possible);
+  return sumBy(possible, (p) => p.sum);
+}
+
+export function evalTry<T>(t: number, index: number, ...choices: T[]): T {
+  const base = choices.length;
+  const choice = Math.max(0, Math.floor(t / Math.pow(base, index - 1)) % base);
+
+  return choices[choice];
+}
+
+export function solveSecond(input: string): number {
+  const regex = /^(\d*): (.*)$/gm;
+  const match = input.matchAll(regex);
+
+  const rows = Array.from(match, (m) => ({
+    sum: Number(m[1]),
+    digits: m[2].split(' ').map((n) => Number(n))
+  }));
+
+  const possible = rows.filter((r) => {
+    for (let t = 0; t < Math.pow(3, r.digits.length - 1); t++) {
+      const sol = r.digits.reduce((sum, curr, i) =>
+        evalTry(t, i, sum * curr, sum + curr, Number(`${sum}${curr}`))
+      );
+      if (sol === r.sum) {
+        return true;
+      }
+    }
+
+    return false;
+  });
+
+  // console.log(possible);
+  return sumBy(possible, (p) => p.sum);
+}

2024/07/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);