aoc/aoc2015/day03.go

package aoc2015

import (
	"aoc/internal/utility"
	"errors"
	"fmt"
)

func day03part1(in string) {
	var x, y int
	houses := make(map[utility.Point]int)
	houses[utility.NewPoint(0, 0)]++

	for _, c := range in {
		switch c {
		case '<':
			x--
		case '>':
			x++
		case 'v':
			y--
		case '^':
			y++
		default:
			utility.E(errors.New("unknown input"))
		}
		houses[utility.NewPoint(x, y)]++
	}
	fmt.Println(len(houses))
}

func day03part2(in string) {
	var (
		sx, sy, rx, ry int
		x, y           *int
	)
	houses := make(map[utility.Point]int)
	houses[utility.NewPoint(0, 0)]++

	for i, c := range in {
		if i%2 == 0 {
			x = &sx
			y = &sy
		} else {
			x = &rx
			y = &ry
		}

		switch c {
		case '<':
			*x--
		case '>':
			*x++
		case 'v':
			*y--
		case '^':
			*y++
		default:
			utility.E(errors.New("unknown input"))
		}

		houses[utility.NewPoint(*x, *y)]++
	}
	fmt.Println(len(houses))
}

func day03() {
	in := utility.GetInput("input/2015/03")
	day03part1(in)
	day03part2(in)
}