add day-08 + benchmarks

day-08/internal/one/antenna.go

@@ -0,0 +1,20 @@
+package one
+
+type coords struct {
+	x int
+	y int
+}
+
+func newCoords(x, y int) coords {
+	return coords{x, y}
+}
+
+type antenna struct {
+	coords
+	identifier rune
+}
+
+func newAntenna(x, y int, identifier rune) antenna {
+	coords := newCoords(x, y)
+	return antenna{coords: coords, identifier: identifier}
+}

day-08/internal/one/benchmark

@@ -0,0 +1,6 @@
+goos: linux
+goarch: amd64
+pkg: github.com/onyx-and-iris/aoc2024/day-08/internal/one
+cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
+BenchmarkSolve-12    	1000000000	         0.0004909 ns/op
+ok  	github.com/onyx-and-iris/aoc2024/day-08/internal/one	0.009s

day-08/internal/one/graph.go

@@ -0,0 +1,32 @@
+package one
+
+import (
+	"strings"
+
+	"github.com/onyx-and-iris/aoc2024/day-08/internal/util"
+)
+
+type graph struct {
+	data      []string
+	antennae  []antenna
+	antinodes map[coords]struct{}
+}
+
+func (g *graph) String() string {
+	return strings.Join(g.data, "\n")
+}
+
+func (g *graph) isOutOfBounds(c coords) bool {
+	return c.x < 0 || c.y < 0 || c.y >= len(g.data) || c.x >= len(g.data[0])
+}
+
+func (g *graph) debug() string {
+	for _, antenna := range g.antennae {
+		g.data[antenna.y] = util.ReplaceAtIndex(g.data[antenna.y], antenna.identifier, antenna.x)
+	}
+	for antinode := range g.antinodes {
+		g.data[antinode.y] = util.ReplaceAtIndex(g.data[antinode.y], '#', antinode.x)
+	}
+
+	return g.String()
+}

day-08/internal/one/solve.go

@@ -0,0 +1,53 @@
+package one
+
+import (
+	"bytes"
+	"math"
+
+	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
+	}
+
+	graph.antinodes = make(map[coords]struct{})
+
+	for i, a := range graph.antennae {
+		for j, b := range graph.antennae {
+			if i == j || a.identifier != b.identifier {
+				continue
+			}
+
+			coords := calcAntiNodePos(a.coords, b.coords)
+			if !graph.isOutOfBounds(coords) {
+				_, ok := graph.antinodes[coords]
+				if !ok {
+					graph.antinodes[coords] = struct{}{}
+				}
+			}
+		}
+	}
+
+	log.Debugf("\n%s\n", graph.debug())
+
+	return len(graph.antinodes), nil
+}
+
+func calcAntiNodePos(a, b coords) coords {
+	xdiff := int(math.Abs(float64(a.x - b.x)))
+	ydiff := int(math.Abs(float64(a.y - b.y)))
+
+	if a.x < b.x && a.y < b.y {
+		return newCoords(b.x+xdiff, b.y+ydiff)
+	} else if a.x < b.x && a.y > b.y {
+		return newCoords(b.x+xdiff, b.y-ydiff)
+	} else if a.x > b.x && a.y < b.y {
+		return newCoords(b.x-xdiff, b.y+ydiff)
+	} else {
+		return newCoords(b.x-xdiff, b.y-ydiff)
+	}
+}

day-08/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-08/internal/one/util.go

@@ -0,0 +1,34 @@
+package one
+
+import (
+	"bufio"
+	"io"
+	"regexp"
+)
+
+var reMatchAntennae = regexp.MustCompile(`[a-zA-Z0-9]`)
+
+func parseLines(r io.Reader) (*graph, error) {
+	var graph graph
+
+	var linecount int
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		line := scanner.Text()
+		graph.data = append(graph.data, line)
+
+		for _, m := range reMatchAntennae.FindAllStringIndex(line, -1) {
+			graph.antennae = append(
+				graph.antennae,
+				newAntenna(m[0], linecount, rune(line[m[0]])),
+			)
+		}
+		linecount++
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	return &graph, nil
+}