index.js

const fs = require('fs');

class Day11 {
  static *parseData(str) {
    let current = '';

    for (const ch of str) {
      if (ch === '\n' || ch === ',') {
        yield current;
        current = '';
      } else if (ch >= 'a' && ch <= 'z') {
        current += ch;
      }
    }
  }

  static getDistance(x, y) {
    const absX = Math.abs(x);
    const absY = Math.abs(y);

    if (absX >= absY) {
      return absX;
    } else {
      return absX + (absY - absX) / 2;
    }
  }

  static run(input) {
    const fileContent = fs.readFileSync(input, 'utf8');
    const directions = this.parseData(fileContent);

    let x = 0;
    let y = 0;
    let max = Number.MIN_SAFE_INTEGER;

    for (const dir of directions) {
      switch (dir) {
        case 'n':
          y += 2;
          break;

        case 's':
          y -= 2;
          break;

        case 'ne':
          x += 1;
          y += 1;
          break;

        case 'se':
          x += 1;
          y -= 1;
          break;

        case 'nw':
          x -= 1;
          y += 1;
          break;

        case 'sw':
          x -= 1;
          y -= 1;
          break;

        default:
          throw new Error('Unexpected direction input!');
      }

      max = Math.max(max, this.getDistance(x, y));
    }

    return [this.getDistance(x, y), max];
  }
}

module.exports = Day11;