Advent of Code 2020 Day 3

advent-of-code-2020-day-3.js

const puzzleInput = ``

// Part 1
const parseInput = (input) => {
  return input.split('\n')
}

const traverse = (rows, colInc, rowInc = 1) => {
  return rows.reduce((acc, row, index) => {
    if (index % rowInc !== 0) { return acc }
    const position = (index / rowInc) * colInc % row.length
    return acc + +(row[position] === '#')
  }, 0)
}

const partOne = (input) => {
  const rows = parseInput(input)
  const treeCount = traverse(rows, 3)
  console.log(treeCount)
}

partOne(puzzleInput)

// Part 2
const partTwo = (input) => {
  const rows = parseInput(input)
  const slopes = [
    [1, 1],
    [3, 1],
    [5, 1],
    [7, 1],
    [1, 2],
  ]
  const treeCount = slopes.reduce((acc, [colInc, rowInc]) => acc * traverse(rows, colInc, rowInc), 1)
  console.log(treeCount)
}

partTwo(puzzleInput)