add day-15 part2 + benchmarks

day-15/internal/one/benchmark

@@ -0,0 +1,6 @@
+goos: linux
+goarch: amd64
+pkg: github.com/onyx-and-iris/aoc2024/day-15/internal/one
+cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
+BenchmarkSolve-12    	1000000000	         0.03920 ns/op
+ok  	github.com/onyx-and-iris/aoc2024/day-15/internal/one	0.322s

day-15/internal/two/benchmark

@@ -0,0 +1,6 @@
+goos: linux
+goarch: amd64
+pkg: github.com/onyx-and-iris/aoc2024/day-15/internal/two
+cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
+BenchmarkSolve-12    	1000000000	         0.07903 ns/op
+ok  	github.com/onyx-and-iris/aoc2024/day-15/internal/two	0.728s

day-15/internal/two/directions.go

@@ -0,0 +1,20 @@
+package two
+
+import "slices"
+
+type direction int
+
+const (
+	N direction = iota
+	NE
+	E
+	SE
+	S
+	SW
+	W
+	NW
+)
+
+func directions(dir rune) direction {
+	return direction(slices.Index([]rune{'^', '.', '>', '.', 'v', '.', '<', '.'}, dir))
+}

day-15/internal/two/explore.go

@@ -0,0 +1,102 @@
+package two
+
+import (
+	log "github.com/sirupsen/logrus"
+
+	orderedmap "github.com/wk8/go-ordered-map/v2"
+)
+
+func exploreDFS(graph *graph, next point, direction direction, stack *stack) (*stack, bool) {
+	ns := neighbours(next)
+
+	log.Debug(string(graph.valueAt(ns[direction])))
+
+	switch graph.valueAt(ns[direction]) {
+	case '#':
+		return nil, false
+	case '.':
+		return stack, true
+	case '[', ']':
+		stack.Push(ns[direction])
+	}
+
+	return exploreDFS(graph, ns[direction], direction, stack)
+}
+
+func exploreBFS(graph *graph, direction direction) (*orderedmap.OrderedMap[point, struct{}], bool) {
+	queue := newQueue()
+	queue.Enqueue(graph.robot)
+	visited := make(map[point]struct{})
+	om := orderedmap.New[point, struct{}]()
+
+	for !queue.IsEmpty() {
+		current := queue.Dequeue().(point)
+
+		_, ok := visited[current]
+		if ok {
+			continue
+		}
+		visited[current] = struct{}{}
+
+		ns := neighbours(current)
+		switch graph.valueAt(ns[direction]) {
+		case '.':
+			if graph.valueAt(current) == '@' {
+				return om, true
+			}
+		case '#':
+			return om, false
+		case '[':
+			log.Debugf("adding %s to the queue", string(graph.valueAt(ns[direction])))
+			queue.Enqueue(ns[direction])
+			_, ok := om.Get(ns[direction])
+			if !ok {
+				om.Set(ns[direction], struct{}{})
+			}
+
+			switch direction {
+			case N:
+				log.Debugf("adding %s to the queue", string(graph.valueAt(ns[NE])))
+				queue.Enqueue(ns[NE])
+				_, ok := om.Get(ns[NE])
+				if !ok {
+					om.Set(ns[NE], struct{}{})
+				}
+			case S:
+				log.Debugf("adding %s to the queue", string(graph.valueAt(ns[SE])))
+				queue.Enqueue(ns[SE])
+				_, ok := om.Get(ns[SE])
+				if !ok {
+					om.Set(ns[SE], struct{}{})
+				}
+			}
+
+		case ']':
+			log.Debugf("adding %s to the queue", string(graph.valueAt(ns[direction])))
+			queue.Enqueue(ns[direction])
+			_, ok := om.Get(ns[direction])
+			if !ok {
+				om.Set(ns[direction], struct{}{})
+			}
+
+			switch direction {
+			case N:
+				log.Debugf("adding %s to the queue", string(graph.valueAt(ns[NW])))
+				queue.Enqueue(ns[NW])
+				_, ok := om.Get(ns[NW])
+				if !ok {
+					om.Set(ns[NW], struct{}{})
+				}
+			case S:
+				log.Debugf("adding %s to the queue", string(graph.valueAt(ns[SW])))
+				queue.Enqueue(ns[SW])
+				_, ok := om.Get(ns[SW])
+				if !ok {
+					om.Set(ns[SW], struct{}{})
+				}
+			}
+		}
+	}
+
+	return om, true
+}

day-15/internal/two/graph.go

@@ -0,0 +1,44 @@
+package two
+
+import (
+	"strings"
+
+	log "github.com/sirupsen/logrus"
+)
+
+type graph struct {
+	robot point
+	data  []string
+}
+
+func newGraph() *graph {
+	return &graph{}
+}
+
+func (g *graph) String() string {
+	return strings.Join(g.data, "\n")
+}
+
+func (g *graph) valueAt(p point) rune {
+	return rune(g.data[p.y][p.x])
+}
+
+func (g *graph) updateRobot(dir direction) {
+	new := neighbours(g.robot)[dir]
+	log.Debugf("new robot point: %v", new)
+
+	g.updateEach(g.robot, '.')
+	g.updateEach(new, '@')
+	g.robot = new
+}
+
+func (g *graph) updateBox(p point, dir direction) {
+	new := neighbours(p)[dir]
+
+	g.updateEach(new, g.valueAt(p))
+	g.updateEach(p, '.')
+}
+
+func (g *graph) updateEach(p point, r rune) {
+	g.data[p.y] = replaceAtIndex(g.data[p.y], r, p.x)
+}

day-15/internal/two/neighbours.go

@@ -0,0 +1,14 @@
+package two
+
+func neighbours(p point) []point {
+	return []point{
+		{p.x, p.y - 1},     // N
+		{p.x + 1, p.y - 1}, // NE
+		{p.x + 1, p.y},     // E
+		{p.x + 1, p.y + 1}, // SE
+		{p.x, p.y + 1},     // S
+		{p.x - 1, p.y + 1}, // SW
+		{p.x - 1, p.y},     // W
+		{p.x - 1, p.y - 1}, // NW
+	}
+}

day-15/internal/two/point.go

@@ -0,0 +1,16 @@
+package two
+
+import "fmt"
+
+type point struct {
+	x int
+	y int
+}
+
+func newPoint(x, y int) point {
+	return point{x, y}
+}
+
+func (p *point) String() string {
+	return fmt.Sprintf("x: %d y: %d", p.x, p.y)
+}

day-15/internal/two/queue.go

@@ -0,0 +1,47 @@
+package two
+
+import (
+	"errors"
+	"fmt"
+)
+
+type queue struct {
+	elements []point
+}
+
+func newQueue() *queue {
+	return &queue{}
+}
+
+func (q *queue) Enqueue(elem point) {
+	q.elements = append(q.elements, elem)
+}
+
+func (q *queue) Dequeue() interface{} {
+	if q.IsEmpty() {
+		fmt.Println("UnderFlow")
+		return point{}
+	}
+	element := q.elements[0]
+	if q.Len() == 1 {
+		q.elements = nil
+		return element
+	}
+	q.elements = q.elements[1:]
+	return element
+}
+
+func (q *queue) Len() int {
+	return len(q.elements)
+}
+
+func (q *queue) IsEmpty() bool {
+	return len(q.elements) == 0
+}
+
+func (q *queue) Peek() (point, error) {
+	if q.IsEmpty() {
+		return point{}, errors.New("empty queue")
+	}
+	return q.elements[0], nil
+}

day-15/internal/two/solve.go

@@ -0,0 +1,66 @@
+package two
+
+import (
+	"bytes"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func Solve(buf []byte) (int, error) {
+	r := bytes.NewReader(buf)
+	graph, dirs, err := parseLines(r)
+	if err != nil {
+		return 0, err
+	}
+
+	log.Debugf("\n%s\n", graph.String())
+
+	for _, dir := range dirs {
+		log.Debugf("about to explore '%s' direction from robot location (%s)", string(dir), graph.robot.String())
+
+		switch directions(dir) {
+		case N, S:
+			exploreNorthSouth(graph, directions(dir))
+		case W, E:
+			exploreWestEast(graph, directions(dir))
+		}
+
+		log.Debugf("\n%s\n", graph.String())
+	}
+
+	var sum int
+	for y, line := range graph.data {
+		for x, r := range line {
+			if r == '[' {
+				sum += (100 * y) + x
+			}
+		}
+	}
+
+	return sum, nil
+}
+
+func exploreWestEast(graph *graph, direction direction) {
+	stack, ok := exploreDFS(graph, graph.robot, direction, newStack())
+	if !ok {
+		log.Debug("path ends with '#', continuing...")
+		return
+	}
+
+	for !stack.IsEmpty() {
+		point := stack.Pop().(point)
+		graph.updateBox(point, direction)
+	}
+	graph.updateRobot(direction)
+}
+
+func exploreNorthSouth(graph *graph, direction direction) {
+	om, ok := exploreBFS(graph, direction)
+
+	if ok {
+		for pair := om.Newest(); pair != nil; pair = pair.Prev() {
+			graph.updateBox(pair.Key, direction)
+		}
+		graph.updateRobot(direction)
+	}
+}

day-15/internal/two/solve_internal_test.go

@@ -0,0 +1,15 @@
+package two
+
+import (
+	_ "embed"
+	"os"
+	"testing"
+)
+
+//go:embed testdata/input.txt
+var data []byte
+
+func BenchmarkSolve(b *testing.B) {
+	os.Stdout, _ = os.Open(os.DevNull)
+	Solve(data)
+}

day-15/internal/two/stack.go

@@ -0,0 +1,33 @@
+package two
+
+type stack struct {
+	items []interface{}
+}
+
+func newStack() *stack {
+	return &stack{}
+}
+
+func (s *stack) Push(element interface{}) interface{} {
+	s.items = append(s.items, element)
+	return element
+}
+
+func (s *stack) Pop() interface{} {
+	l := len(s.items)
+	element := s.items[l-1]
+	s.items = s.items[:l-1]
+	return element
+}
+
+func (s *stack) Peek() interface{} {
+	return s.items[len(s.items)-1]
+}
+
+func (s *stack) Len() int {
+	return len(s.items)
+}
+
+func (s *stack) IsEmpty() bool {
+	return s.Len() == 0
+}

day-15/internal/two/util.go

@@ -0,0 +1,70 @@
+package two
+
+import (
+	"bufio"
+	"io"
+	"strings"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func parseLines(r io.Reader) (*graph, string, error) {
+	graph := newGraph()
+	var directions []string
+
+	var sb strings.Builder
+	var inDirections bool
+	var linecount int
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if len(line) == 0 {
+			inDirections = true
+			continue
+		}
+
+		if inDirections {
+			directions = append(directions, line)
+		} else {
+			for _, r := range line {
+				switch r {
+				case '#':
+					sb.WriteRune('#')
+					sb.WriteRune('#')
+				case 'O':
+					sb.WriteRune('[')
+					sb.WriteRune(']')
+				case '@':
+					sb.WriteRune('@')
+					sb.WriteRune('.')
+				default:
+					sb.WriteRune('.')
+					sb.WriteRune('.')
+				}
+			}
+
+			indx := strings.Index(sb.String(), "@")
+			if indx != -1 {
+				log.Debugf("adding start point at (%d, %d)", indx, linecount)
+				graph.robot = newPoint(indx, linecount)
+			}
+
+			graph.data = append(graph.data, sb.String())
+			sb.Reset()
+		}
+
+		linecount++
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, "", err
+	}
+
+	return graph, strings.Join(directions, ""), nil
+}
+
+func replaceAtIndex(s string, r rune, i int) string {
+	out := []rune(s)
+	out[i] = r
+	return string(out)
+}