adventofcode/2023/day11/main.go

package main

import (
	"fmt"

	h "git.bullercodeworks.com/brian/adventofcode/helpers"
)

func main() {
	inp := h.StdinToStringSlice()
	part1(inp)
	fmt.Println()
	part2(inp)
}

func part1(input []string) {
	m := h.StringSliceToCoordByteMap(input)
	for y := m.Height() - 1; y >= 0; y-- {
		if !m.RowContains(y, '#') {
			m.InsertRowAfter(y, '.')
		}
	}
	for x := m.Width() - 1; x >= 0; x-- {
		if !m.ColContains(x, '#') {
			m.InsertColAfter(x, '.')
		}
	}
	galaxies := m.FindAll('#')
	var result int
	for i := 0; i < len(galaxies); i++ {
		for j := i + 1; j < len(galaxies); j++ {
			result += galaxies[i].Distance(galaxies[j])
		}
	}
	fmt.Println("# Part 1")
	fmt.Println(result)
}

func part2(input []string) {
	m := h.StringSliceToCoordByteMap(input)
	expansion := 1000000

	galaxies := m.FindAll('#')
	for y := m.Height() - 1; y >= 0; y-- {
		if !m.RowContains(y, '#') {
			// For every '#' coordinate on a row _after_ y, add 1000000 to it's y coord
			for i := 0; i < len(galaxies); i++ {
				if galaxies[i].Y > y {
					galaxies[i].Y += (expansion - 1)
				}
			}
		}
	}
	for x := m.Width() - 1; x >= 0; x-- {
		if !m.ColContains(x, '#') {
			// For every '#' coordinate on a col _after_ x, add 1000000 to it's x coord
			for i := 0; i < len(galaxies); i++ {
				if galaxies[i].X > x {
					galaxies[i].X += (expansion - 1)
				}
			}
		}
	}
	var result int
	for i := 0; i < len(galaxies); i++ {
		for j := i + 1; j < len(galaxies); j++ {
			result += galaxies[i].Distance(galaxies[j])
		}
	}
	fmt.Println("# Part 2")
	fmt.Println(result)
}