add day-12 + benchmarks

day-12/internal/one/benchmark

@@ -0,0 +1,6 @@
+goos: linux
+goarch: amd64
+pkg: github.com/onyx-and-iris/aoc2024/day-12/internal/one
+cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
+BenchmarkSolve-12    	1000000000	         0.03239 ns/op
+ok  	github.com/onyx-and-iris/aoc2024/day-12/internal/one	0.236s

day-12/internal/one/direction.go

@@ -0,0 +1,8 @@
+package one
+
+const (
+	N = iota
+	E
+	S
+	W
+)

day-12/internal/one/explore.go

@@ -0,0 +1,37 @@
+package one
+
+import (
+	"github.com/onyx-and-iris/aoc2024/day-12/internal/queue"
+)
+
+func explore(start point, graph *graph) path {
+	queue := queue.New[point]()
+	queue.Enqueue(start)
+	visited := make(map[point]struct{})
+	var perimeter int
+
+	for !queue.IsEmpty() {
+		current := queue.Dequeue()
+
+		_, ok := visited[current]
+		if ok {
+			continue
+		}
+		visited[current] = struct{}{}
+
+		for _, n := range neighbours(current) {
+			if graph.isOutOfBounds(n) {
+				perimeter++
+				continue
+			}
+
+			if graph.valueAt(n) != graph.valueAt(current) {
+				perimeter++
+				continue
+			}
+			queue.Enqueue(n)
+		}
+	}
+
+	return path{visited, perimeter}
+}

day-12/internal/one/graph.go

@@ -0,0 +1,46 @@
+package one
+
+import (
+	"slices"
+	"strings"
+
+	log "github.com/sirupsen/logrus"
+)
+
+type point struct {
+	x int
+	y int
+}
+
+func newPoint(x, y int) point {
+	return point{x, y}
+}
+
+type graph struct {
+	data []string
+}
+
+func newGraph() *graph {
+	return &graph{}
+}
+
+func (g *graph) String() string {
+	return strings.Join(g.data, "\n")
+}
+
+func (g *graph) isOutOfBounds(p point) bool {
+	return p.x < 0 || p.y < 0 || p.y >= len(g.data) || p.x >= len(g.data[p.y])
+}
+
+func (g *graph) valueAt(p point) rune {
+	return rune(g.data[p.y][p.x])
+}
+
+func (g *graph) debug(visited map[point]struct{}) string {
+	log.Debugf("path for %s", string(g.valueAt(firstPointFromMap(visited))))
+	temp := slices.Clone(g.data)
+	for point := range visited {
+		temp[point.y] = replaceAtIndex(temp[point.y], 'x', point.x)
+	}
+	return strings.Join(temp, "\n")
+}

day-12/internal/one/neighbours.go

@@ -0,0 +1,10 @@
+package one
+
+func neighbours(p point) [4]point {
+	return [4]point{
+		{p.x, p.y - 1}, // N
+		{p.x + 1, p.y}, // E
+		{p.x, p.y + 1}, // S
+		{p.x - 1, p.y}, // W
+	}
+}

day-12/internal/one/path.go

@@ -0,0 +1,6 @@
+package one
+
+type path struct {
+	visited   map[point]struct{}
+	perimeter int
+}

day-12/internal/one/solve.go

@@ -0,0 +1,42 @@
+package one
+
+import (
+	"bytes"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func Solve(buf []byte) (int, error) {
+	r := bytes.NewReader(buf)
+	graph, err := parseLines(r)
+	if err != nil {
+		return 0, err
+	}
+
+	var totalCost int
+	totalAreaVisited := make(map[point]struct{})
+	for i := 0; i < len(graph.data); i++ {
+		for j := 0; j < len(graph.data[i]); j++ {
+			start := newPoint(j, i)
+			if graph.isOutOfBounds(start) {
+				continue
+			}
+
+			_, ok := totalAreaVisited[start]
+			if ok {
+				continue
+			}
+			totalAreaVisited[start] = struct{}{}
+
+			path := explore(start, graph)
+			log.Debugf("\n%s\n", graph.debug(path.visited))
+			totalCost += len(path.visited) * path.perimeter
+
+			for point := range path.visited {
+				totalAreaVisited[point] = struct{}{}
+			}
+		}
+	}
+
+	return totalCost, nil
+}

day-12/internal/one/solve_internal_test.go

@@ -0,0 +1,15 @@
+package one
+
+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-12/internal/one/util.go

@@ -0,0 +1,35 @@
+package one
+
+import (
+	"bufio"
+	"io"
+	"maps"
+)
+
+func parseLines(r io.Reader) (*graph, error) {
+	graph := newGraph()
+
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		graph.data = append(graph.data, scanner.Text())
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	return graph, nil
+}
+
+func replaceAtIndex(s string, r rune, i int) string {
+	out := []rune(s)
+	out[i] = r
+	return string(out)
+}
+
+func firstPointFromMap(visited map[point]struct{}) point {
+	for k := range maps.Keys(visited) {
+		return k
+	}
+	panic("unable to fetch points from map")
+}