Port 2017/22 from Python to Go

other/go/2017.22.go

@@ -0,0 +1,103 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"maps"
+	"slices"
+	"strings"
+)
+
+type Rotation int
+type virusState int
+
+const (
+	rotateRight    Rotation   = iota
+	rotateLeft     Rotation   = iota
+	rotateReverse  Rotation   = iota
+	rotateStraight Rotation   = iota
+	clean          virusState = iota
+	weakened       virusState = iota
+	infected       virusState = iota
+	flagged        virusState = iota
+	steps1                    = 10000
+	steps2                    = 10000000
+)
+
+var (
+	nextState1 = map[virusState]virusState{clean: infected, infected: clean}
+	nextState2 = map[virusState]virusState{clean: weakened, weakened: infected, infected: flagged, flagged: clean}
+	rotations  = map[virusState]Rotation{clean: rotateLeft, weakened: rotateStraight, infected: rotateRight, flagged: rotateReverse}
+)
+
+type Location struct {
+	x, y int
+}
+
+func (l *Location) Advance(d *Direction) {
+	l.x += d.dx
+	l.y += d.dy
+}
+
+type Direction struct {
+	dx, dy int
+}
+
+func (d *Direction) Rotate(rotation Rotation) {
+	switch rotation {
+	case rotateRight:
+		d.dx, d.dy = +1*d.dy, -1*d.dx
+	case rotateLeft:
+		d.dx, d.dy = -1*d.dy, +1*d.dx
+	case rotateReverse:
+		d.dx, d.dy = -1*d.dx, -1*d.dy
+	case rotateStraight:
+	}
+}
+
+type Simulation struct {
+	*Location
+	*Direction
+	nodes    map[Location]virusState
+	infected int
+}
+
+func (s *Simulation) Run(steps int, states map[virusState]virusState) {
+	for range steps {
+		state, ok := s.nodes[*s.Location]
+		if !ok {
+			state = clean
+		}
+		s.Direction.Rotate(rotations[state])
+		s.nodes[*s.Location] = states[state]
+		if s.nodes[*s.Location] == infected {
+			s.infected++
+		}
+		s.Advance(s.Direction)
+	}
+}
+
+func main() {
+	data, err := ioutil.ReadFile("2017/22.txt")
+	if err != nil {
+		panic("Failed to read file")
+	}
+	lines := strings.Split(strings.TrimRight(string(data), "\n"), "\n")
+	slices.Reverse(lines)
+	nodes := make(map[Location]virusState)
+	for y, line := range lines {
+		for x, char := range line {
+			if char == '#' {
+				nodes[Location{x, y}] = infected
+			}
+		}
+	}
+	center := (len(lines) - 1) / 2
+	nodes2 := maps.Clone(nodes)
+	s := &Simulation{&Location{center, center}, &Direction{0, 1}, nodes, 0}
+	s.Run(steps1, nextState1)
+	fmt.Printf("Part 1: Robot infected %d locations. Correct: %v\n", s.infected, s.infected == 5261)
+	s = &Simulation{&Location{center, center}, &Direction{0, 1}, nodes2, 0}
+	s.Run(steps2, nextState2)
+	fmt.Printf("Part 2: Robot infected %d locations. Correct: %v\n", s.infected, s.infected == 2511927)
+}