2019/day3/main.go

package main

import (
	"bufio"
	"log"
	"math"
	"os"
	"strconv"
	"strings"
)

type Point struct {
	X int
	Y int
}

func main() {
	file, err := os.Open("input.txt")
	if err != nil {
		log.Fatal(err)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	if !scanner.Scan() {
		log.Fatalln("Problem while read line.")
		return
	}
	route1 := scanner.Text()
	if !scanner.Scan() {
		log.Fatalln("Problem while read second line.")
		return
	}
	route2 := scanner.Text()
	distance := GetShortestDistance(route1, route2)
	routeDistance := GetShortestRoute(route1, route2)

	log.Println("Part1: Distance: " + strconv.Itoa(distance))
	log.Println("Part2: Route: " + strconv.Itoa(routeDistance))

}

func GetShortestDistance(route1 string, route2 string) int {
	points1 := GetAllPointsFromRoute(ParseRoute(route1))
	points2 := GetAllPointsFromRoute(ParseRoute(route2))
	crossed := FindAllCrossedPoints(points1, points2)
	distance := GetShortestDistanceFromPoints(crossed)
	return distance
}

func GetShortestRoute(route1 string, route2 string) int {
	points1 := GetAllPointsFromRoute(ParseRoute(route1))
	points2 := GetAllPointsFromRoute(ParseRoute(route2))
	crossed := FindAllCrossedPoints(points1, points2)

	shortestDis := math.MaxInt32
	for _, point := range crossed {
		distance1 := GetRouteDistanceToPoint(points1, point)
		distance2 := GetRouteDistanceToPoint(points2, point)
		fullDistance := distance1 + distance2
		if fullDistance < shortestDis {
			shortestDis = fullDistance
		}
	}
	return shortestDis
}

func ParseRoute(route string) []string {
	return strings.Split(route, ",")
}

func GetAllPointsFromRoute(cmds []string) []Point {
	var (
		currentX int
		currentY int
		points   []Point
	)

	for _, cmd := range cmds {
		runes := []rune(cmd)
		direction := string(runes[0])
		lengthStr := string(runes[1:len(runes)])
		length, _ := strconv.Atoi(lengthStr)

		if direction == "R" {
			for i := 1; i <= length; i++ {
				currentX++
				points = append(points, Point{X: currentX, Y: currentY})
			}
		} else if direction == "L" {
			for i := 1; i <= length; i++ {
				currentX--
				points = append(points, Point{X: currentX, Y: currentY})
			}
		} else if direction == "U" {
			for i := 1; i <= length; i++ {
				currentY++
				points = append(points, Point{X: currentX, Y: currentY})
			}
		} else if direction == "D" {
			for i := 1; i <= length; i++ {
				currentY--
				points = append(points, Point{X: currentX, Y: currentY})
			}
		} else {
			log.Fatal("ERROR Cmd: " + direction)
		}
	}
	return points
}

func FindAllCrossedPoints(a []Point, b []Point) []Point {
	crossedPoints := make([]Point, 0)

	for _, pointA := range a {
		for _, pointB := range b {
			if pointA.X == pointB.X && pointA.Y == pointB.Y {
				crossedPoints = append(crossedPoints, pointA)
			}
		}
	}
	return crossedPoints
}

func GetShortestDistanceFromPoints(points []Point) int {
	shortestDis := math.MaxInt32
	for _, point := range points {
		distance := GetDistanceFromPoint(point)
		if distance < shortestDis {
			shortestDis = distance
		}
	}
	return shortestDis
}

func GetRouteDistanceToPoint(route []Point, point Point) int {
	sum := 0
	for _, routePoint := range route {
		sum++
		if routePoint.X == point.X && routePoint.Y == point.Y {
			break
		}
	}
	return sum
}

func GetDistanceFromPoint(point Point) int {
	return GetPositiveNumber(point.X) + GetPositiveNumber(point.Y)
}

func GetPositiveNumber(num int) int {
	if num < 0 {
		return -1 * num
	}
	return num
}