Solve 2024-10

2024/10/2024-10.run.xml

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+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="2024-10" type="BunRunConfiguration">
+    <option name="program" value="2024/10/run.ts" />
+    <option name="workingDirectory" value="$PROJECT_DIR$" />
+    <method v="2" />
+  </configuration>
+</component>

2024/10/index.test.ts

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+import { describe, expect, it } from 'bun:test';
+import { solveFirst, solveSecond } from './index.ts';
+
+describe('2024-10', () => {
+  const testInput = `89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732`;
+  it('first', () => {
+    expect(
+      solveFirst(`0123
+1234
+8765
+9876`)
+    ).toBe(1);
+    expect(
+      solveFirst(`...0...
+...1...
+...2...
+6543456
+7.....7
+8.....8
+9.....9`)
+    ).toBe(2);
+    expect(
+      solveFirst(`..90..9
+...1.98
+...2..7
+6543456
+765.987
+876....
+987....`)
+    ).toBe(4);
+    expect(
+      solveFirst(`10..9..
+2...8..
+3...7..
+4567654
+...8..3
+...9..2
+.....01`)
+    ).toBe(3);
+
+    expect(solveFirst(testInput)).toBe(36);
+  });
+  it('second', () => {
+    expect(
+      solveSecond(`.....0.
+..4321.
+..5..2.
+..6543.
+..7..4.
+..8765.
+..9....`)
+    ).toBe(3);
+
+    expect(
+      solveSecond(`..90..9
+...1.98
+...2..7
+6543456
+765.987
+876....
+987....`)
+    ).toBe(13);
+    expect(
+      solveSecond(`012345
+123456
+234567
+345678
+4.6789
+56789.`)
+    ).toBe(227);
+    expect(solveSecond(testInput)).toBe(81);
+  });
+});

2024/10/index.ts

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+import { sumArray, unique } from '../../utils/array.ts';
+import {
+  type Coordinates,
+  findCoordsOfDigit,
+  getAdjacent,
+  isCoordinateEqual
+} from '../../utils/coordinates.ts';
+
+export function getScoreOfHead(
+  rows: string[],
+  startX: number,
+  startY: number,
+  startDigit = 0
+): Coordinates {
+  if (startDigit >= 9) {
+    return [[startX, startY]];
+  }
+
+  const top = rows[startY - 1]?.[startX];
+  const right = rows[startY]?.[startX + 1];
+  const down = rows[startY + 1]?.[startX];
+  const left = rows[startY]?.[startX - 1];
+
+  let found: Coordinates = [];
+  const lookFor = startDigit + 1;
+
+  if (top && Number(top) === lookFor) {
+    found.push(...getScoreOfHead(rows, startX, startY - 1, lookFor));
+  }
+  if (right && Number(right) === lookFor) {
+    found.push(...getScoreOfHead(rows, startX + 1, startY, lookFor));
+  }
+  if (down && Number(down) === lookFor) {
+    found.push(...getScoreOfHead(rows, startX, startY + 1, lookFor));
+  }
+  if (left && Number(left) === lookFor) {
+    found.push(...getScoreOfHead(rows, startX - 1, startY, lookFor));
+  }
+
+  return found;
+}
+
+export function solveFirst(input: string): number {
+  const rows = input.split('\n');
+
+  const trailHeads = findCoordsOfDigit(rows, '0');
+
+  const scores = trailHeads.map(
+    ([startX, startY]) =>
+      getScoreOfHead(rows, startX, startY).filter(unique(isCoordinateEqual))
+        .length
+  );
+
+  return sumArray(scores);
+}
+
+export function getRatingOfHead(
+  rows: string[],
+  startX: number,
+  startY: number,
+  startDigit = 0
+): Coordinates[] {
+  if (startDigit >= 9) {
+    return [[[startX, startY]]];
+  }
+
+  const { top, right, left, down } = getAdjacent(rows, startX, startY);
+
+  let found: Coordinates[] = [];
+  const lookFor = startDigit + 1;
+
+  if (top && Number(top) === lookFor) {
+    found.push(...getRatingOfHead(rows, startX, startY - 1, lookFor));
+  }
+  if (right && Number(right) === lookFor) {
+    found.push(...getRatingOfHead(rows, startX + 1, startY, lookFor));
+  }
+  if (down && Number(down) === lookFor) {
+    found.push(...getRatingOfHead(rows, startX, startY + 1, lookFor));
+  }
+  if (left && Number(left) === lookFor) {
+    found.push(...getRatingOfHead(rows, startX - 1, startY, lookFor));
+  }
+
+  return found;
+}
+
+export function solveSecond(input: string): number {
+  const rows = input.split('\n');
+
+  const trailHeads = findCoordsOfDigit(rows, '0');
+
+  const scores = trailHeads.map(
+    ([startX, startY]) => getRatingOfHead(rows, startX, startY).length
+  );
+
+  return sumArray(scores);
+}

2024/10/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);