2019 Day 3 done!

2019/day03/main.go

@@ -0,0 +1,125 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"math"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const MaxInt = int(^uint(0) >> 1)
+
+func main() {
+	inp := 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 := 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)))
+}
+
+func StdinToStringSlice() []string {
+	var input []string
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		input = append(input, scanner.Text())
+	}
+	return input
+}
+
+func Atoi(i string) int {
+	var ret int
+	var err error
+	if ret, err = strconv.Atoi(i); err != nil {
+		log.Fatal("Invalid Atoi")
+	}
+	return ret
+}