Discussion on: Advent of Code 2020 Solution Megathread - Day 3: Toboggan Trajectory

[Stefan Linke]

A bit of Go

package main

import (
    "fmt"
)

const (
    SymbolTree  byte = '#'
    SymbolEmpty      = '.'
)

func checkPath(grid [][]byte, height, width int, path []int) int {
    numTrees := 0
    for x, y := 0, 0; y < height; {
        if grid[y][x] == SymbolTree {
            numTrees++
        }

        x = (x + path[0]) % width
        y += path[1]
    }

    return numTrees
}

func main() {
    grid := make([][]byte, 400)
    height := 0

    for {
        if _, err := fmt.Scanln(&grid[height]); err != nil {
            break
        }
        height++
    }

    width := len(grid[0])
    fmt.Println("part 1:", checkPath(grid, height, width, []int{3, 1}))

    part2 := checkPath(grid, height, width, []int{1, 1})
    part2 *= checkPath(grid, height, width, []int{3, 1})
    part2 *= checkPath(grid, height, width, []int{5, 1})
    part2 *= checkPath(grid, height, width, []int{7, 1})
    part2 *= checkPath(grid, height, width, []int{1, 2})
    fmt.Println("part 2:", part2)
}