add day-14 + benchmarks

day-14/internal/two/benchmark

@@ -0,0 +1,6 @@
+goos: linux
+goarch: amd64
+pkg: github.com/onyx-and-iris/aoc2024/day-14/internal/two
+cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
+BenchmarkSolve-12    	1000000000	         0.4504 ns/op
+ok  	github.com/onyx-and-iris/aoc2024/day-14/internal/two	11.186s

day-14/internal/two/graph.go

@@ -0,0 +1,59 @@
+package two
+
+import (
+	"strings"
+)
+
+type dimension int
+
+type graph struct {
+	x    dimension
+	y    dimension
+	data [][]int
+}
+
+func newGraph(x, y dimension) *graph {
+	var data [][]int
+	for range y {
+		data = append(data, make([]int, x))
+	}
+
+	return &graph{x: x, y: y, data: data}
+}
+
+func (g *graph) String() string {
+	temp := []string{}
+	for range len(g.data) {
+		temp = append(temp, string(make([]byte, len(g.data[0]))))
+	}
+
+	for i := 0; i < len(g.data); i++ {
+		for j := 0; j < len(g.data[0]); j++ {
+			if g.data[i][j] == 0 {
+				temp[i] = replaceAtIndex(temp[i], '.', j)
+			} else {
+				temp[i] = replaceAtIndex(temp[i], '*', j)
+			}
+		}
+	}
+
+	return strings.Join(temp, "\n")
+}
+
+func (g *graph) update(robots []*robot) {
+	for _, robot := range robots {
+		g.updateEach(robot.position)
+	}
+}
+
+func (g *graph) updateEach(p position) {
+	g.data[p.y][p.x]++
+}
+
+func (g *graph) isOutOfBounds(p position) 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 position) int {
+	return g.data[p.y][p.x]
+}

day-14/internal/two/neighbours.go

@@ -0,0 +1,14 @@
+package two
+
+func neighbours(p position) [8]position {
+	return [8]position{
+		{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-14/internal/two/robot.go

@@ -0,0 +1,51 @@
+package two
+
+import (
+	"fmt"
+)
+
+type position struct {
+	x int
+	y int
+}
+
+type velocity struct {
+	x int
+	y int
+}
+
+type robot struct {
+	position position
+	velocity velocity
+}
+
+func newRobot(px, py, vx, vy int) *robot {
+	return &robot{
+		position{x: px, y: py},
+		velocity{x: vx, y: vy},
+	}
+}
+
+func (r *robot) String() string {
+	return fmt.Sprintf("position: %+v velocity: %+v", r.position, r.velocity)
+}
+
+func (r *robot) update(width, height dimension) position {
+	oldPosition := r.position
+
+	r.position.x += r.velocity.x
+	if r.position.x < 0 {
+		r.position.x = int(width) + r.position.x
+	} else if r.position.x >= int(width) {
+		r.position.x = r.position.x - int(width)
+	}
+
+	r.position.y += r.velocity.y
+	if r.position.y < 0 {
+		r.position.y = int(height) + r.position.y
+	} else if r.position.y >= int(height) {
+		r.position.y = r.position.y - int(height)
+	}
+
+	return oldPosition
+}

day-14/internal/two/solve.go

@@ -0,0 +1,55 @@
+package two
+
+import (
+	"bytes"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func Solve(buf []byte) (int, error) {
+	r := bytes.NewReader(buf)
+	robots, err := parseLines(r)
+	if err != nil {
+		return 0, err
+	}
+
+	const maxSeconds int = 10e3
+	const width, height dimension = 101, 103
+
+	var graph *graph
+	var max, maxAtSecond int
+	for i := 1; i <= maxSeconds; i++ {
+		graph = newGraph(width, height)
+
+		for _, robot := range robots {
+			robot.update(width, height)
+		}
+		graph.update(robots)
+
+		numNeighbours := evaluateNeighbours(graph, robots)
+		if numNeighbours > max {
+			max = numNeighbours
+			maxAtSecond = i
+		}
+	}
+
+	log.Debugf("\n%s\n", graph.String())
+
+	return maxAtSecond, nil
+}
+
+func evaluateNeighbours(graph *graph, robots []*robot) int {
+	var numNeighbours int
+	for _, robot := range robots {
+		for _, n := range neighbours(robot.position) {
+			if graph.isOutOfBounds(n) {
+				continue
+			}
+
+			if graph.valueAt(n) > 0 {
+				numNeighbours++
+			}
+		}
+	}
+	return numNeighbours
+}

day-14/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-14/internal/two/util.go

@@ -0,0 +1,46 @@
+package two
+
+import (
+	"bufio"
+	"io"
+	"regexp"
+	"strconv"
+)
+
+var reRobot = regexp.MustCompile(`p=(?P<px>\d+),(?P<py>\d+) v=(?P<vx>-?\d+),(?P<vy>-?\d+)`)
+
+func parseLines(r io.Reader) ([]*robot, error) {
+	var matches [][]string
+
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		line := scanner.Text()
+		m := reRobot.FindStringSubmatch(line)
+		matches = append(matches, m)
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	var robots []*robot
+	for _, m := range matches {
+		robots = append(robots, newRobot(mustConv(m[1]), mustConv(m[2]), mustConv(m[3]), mustConv(m[4])))
+	}
+
+	return robots, nil
+}
+
+func mustConv(s string) int {
+	n, err := strconv.Atoi(s)
+	if err != nil {
+		panic(err)
+	}
+	return n
+}
+
+func replaceAtIndex(s string, r rune, i int) string {
+	out := []rune(s)
+	out[i] = r
+	return string(out)
+}