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main.go
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main.go
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package main
import (
"bufio"
"flag"
"fmt"
"os"
"slices"
"strconv"
"strings"
)
var (
methodP *string
)
func parseFlags() {
methodP = flag.String("method", "all", "The method/part that should be run, valid are p1,p2 and test")
flag.Parse()
}
func main() {
parseFlags()
switch *methodP {
case "all":
fmt.Println("Silver:" + PartOne("input"))
fmt.Println("Gold:" + PartTwo("input", 1000000))
case "p1":
fmt.Println("Silver:" + PartOne("input"))
case "p2":
fmt.Println("Gold:" + PartTwo("input", 1000000))
}
}
type Point struct {
x int
y int
}
func PartOne(filename string) string {
input := readInput(filename)
// First expand galaxy
expandedGalaxy := ExpandGalaxy(input)
// Find each Galaxy
galaxies := findGoals(expandedGalaxy)
totalDistance := 0
for len(galaxies) != 0 {
checkGalaxy := galaxies[0]
galaxies = galaxies[1:]
// Distance between each pair
for _, g := range galaxies {
totalDistance += ManhattenDistance(checkGalaxy, g)
}
}
num := strconv.Itoa(totalDistance)
return num
}
func ExpandGalaxy(input []string) []string {
var expanded []string
// Expand each row
for _, v := range input {
if strings.Contains(v, "#") {
expanded = append(expanded, v)
} else {
expanded = append(expanded, v, v)
}
}
// Transpose
var transpose []string
for i := 0; i < len(expanded[0]); i++ {
transposeLine := ""
for _, v := range expanded {
transposeLine += string(v[i])
}
transpose = append(transpose, transposeLine)
}
// Then expand each column
var expanded_2 []string
for _, v := range transpose {
if strings.Contains(v, "#") {
expanded_2 = append(expanded_2, v)
} else {
expanded_2 = append(expanded_2, v, v)
}
}
// Transpose again
var transpose_2 []string
for i := 0; i < len(expanded_2[0]); i++ {
transposeLine := ""
for _, v := range expanded_2 {
transposeLine += string(v[i])
}
transpose_2 = append(transpose_2, transposeLine)
}
// Then return
return transpose_2
}
func findGoals(input []string) []Point {
// Find E point in input
var points []Point
for y, line := range input {
for x, v := range line {
if string(v) == "#" {
points = append(points, Point{x, y})
}
}
}
return points
}
// Figure out the Manhatten Distance between two points
func ManhattenDistance(firstPoint Point, secondPoint Point) int {
x := abs(firstPoint.x - secondPoint.x)
y := abs(firstPoint.y - secondPoint.y)
return x + y
}
// Absoulute value of Int
func abs(x int) int {
if x < 0 {
return -x
} else {
return x
}
}
func PartTwo(filename string, size int) string {
input := readInput(filename)
// Find rows that are "expanded"
expandedRows := ExpandGalaxyRows(input)
// Find columns that are "expanded"
expandedColumns := ExpandGalaxyColumns(input)
// Find each Galaxy
galaxies := findGoals(input)
totalDistance := 0
for len(galaxies) != 0 {
checkGalaxy := galaxies[0]
galaxies = galaxies[1:]
// Distance between each pair
for _, g := range galaxies {
totalDistance += GalaxyDistance(checkGalaxy, g, expandedRows, expandedColumns, size)
}
}
num := strconv.Itoa(totalDistance)
return num
}
func ExpandGalaxyRows(input []string) []int {
var expanded []int
// Expand each row
for i, v := range input {
if !strings.Contains(v, "#") {
expanded = append(expanded, i)
}
}
// Then return
return expanded
}
func ExpandGalaxyColumns(input []string) []int {
var expanded []int
// Transpose
var transpose []string
for i := 0; i < len(input[0]); i++ {
transposeLine := ""
for _, v := range input {
transposeLine += string(v[i])
}
transpose = append(transpose, transposeLine)
}
// Expand each row
for i, v := range transpose {
if !strings.Contains(v, "#") {
expanded = append(expanded, i)
}
}
// Then return
return expanded
}
// Figure out the "Galaxy" Distance between two points
func GalaxyDistance(firstPoint Point, secondPoint Point, expandedRows, expandedColumns []int, size int) int {
distance := 0
// Work out X
// Always go from left to right
if firstPoint.x < secondPoint.x {
for i := firstPoint.x; i < secondPoint.x; i++ {
if slices.Contains(expandedColumns, i) {
distance += size
} else {
distance += 1
}
}
} else {
for i := secondPoint.x; i < firstPoint.x; i++ {
if slices.Contains(expandedColumns, i) {
distance += size
} else {
distance += 1
}
}
}
// Work out Y
// Always go from top to bottom
if firstPoint.y < secondPoint.y {
for i := firstPoint.y; i < secondPoint.y; i++ {
if slices.Contains(expandedRows, i) {
distance += size
} else {
distance += 1
}
}
} else {
for i := secondPoint.y; i < firstPoint.y; i++ {
if slices.Contains(expandedRows, i) {
distance += size
} else {
distance += 1
}
}
}
return distance
}
// Read data from input.txt
// Return the string, so that we can deal with it however
func readInput(filename string) []string {
var input []string
f, _ := os.Open(filename + ".txt")
scanner := bufio.NewScanner(f)
for scanner.Scan() {
input = append(input, scanner.Text())
}
return input
}
// Read data from input.txt
// Return the string as int
func readInputInt() []int {
var input []int
f, _ := os.Open("input.txt")
scanner := bufio.NewScanner(f)
for scanner.Scan() {
num, _ := strconv.Atoi(scanner.Text())
input = append(input, num)
}
return input
}