adventofcode/2019/day03/main.go

package main

import (
	"fmt"
	helpers "git.bullercodeworks.com/brian/adventofcode/helpers"
	"math"
	"strings"
)

const MaxInt = int(^uint(0) >> 1)

func main() {
	inp := helpers.StdinToStringSlice()
	part1(inp)
}

func part1(inp []string) {
	var allWires []*Wire
	for _, v := range inp {
		wire := NewWire()
		wrk := strings.Split(v, ",")
		for _, p := range wrk {
			wire.Go(p)
		}
		allWires = append(allWires, wire)
	}
	var shortestCoord, fewestStepsCoord Coord
	shortest := MaxInt
	shortestSteps := MaxInt
	for p1i, p1 := range allWires[0].path {
		if p1.x == 0 && p1.y == 0 {
			continue
		}
		for p2i, p2 := range allWires[1].path {
			if p2.x == 0 && p2.y == 0 {
				continue
			}
			if p1.equals(p2) {
				wrk := manhattanDistance(p1.x, p1.y, 0, 0)
				if wrk < shortest {
					shortest = wrk
					shortestCoord = p1
				}
				if p1i+p2i < shortestSteps {
					shortestSteps = p1i + p2i
					fewestStepsCoord = p1
				}
			}
		}
	}
	fmt.Println("Closest:", shortest, shortestCoord)
	fmt.Println("Fewest Steps:", shortestSteps, fewestStepsCoord)
}

type Wire struct {
	curr Coord
	path []Coord
}

func NewWire() *Wire {
	w := Wire{}
	w.curr = Coord{0, 0}
	w.path = append(w.path, w.curr)
	return &w
}

func (w *Wire) Go(cmd string) {
	dir := cmd[0]
	length := helpers.Atoi(cmd[1:])
	for length > 0 {
		w.Move(dir)
		w.path = append(w.path, w.curr)
		length--
	}
}

func (w *Wire) Move(dir byte) {
	switch dir {
	case 'U':
		w.curr = Coord{w.curr.x, w.curr.y - 1}
	case 'R':
		w.curr = Coord{w.curr.x + 1, w.curr.y}
	case 'D':
		w.curr = Coord{w.curr.x, w.curr.y + 1}
	case 'L':
		w.curr = Coord{w.curr.x - 1, w.curr.y}
	}
}

type Coord struct {
	x, y int
}

func (c Coord) equals(b Coord) bool {
	return c.x == b.x && c.y == b.y
}

func (c Coord) string() string {
	return fmt.Sprintf("{%2d,%2d}", c.x, c.y)
}

func manhattanDistance(x1, y1, x2, y2 int) int {
	return int(math.Abs(float64(x1)-float64(x2)) + math.Abs(float64(y1)-float64(y2)))
}