add day-16 part1

day-16/.gitignore

@@ -0,0 +1 @@
+internal/two

day-16/cmd/cli/main.go

@@ -0,0 +1,41 @@
+/********************************************************************************
+    Advent of Code 2024 - day-16
+********************************************************************************/
+
+package main
+
+import (
+	"embed"
+	"flag"
+	"fmt"
+	"slices"
+
+	log "github.com/sirupsen/logrus"
+
+	problems "github.com/onyx-and-iris/aoc2024/day-16"
+)
+
+//go:embed testdata
+var files embed.FS
+
+func main() {
+	filename := flag.String("f", "input.txt", "input file")
+	loglevel := flag.Int("l", int(log.InfoLevel), "log level")
+	flag.Parse()
+
+	if slices.Contains(log.AllLevels, log.Level(*loglevel)) {
+		log.SetLevel(log.Level(*loglevel))
+	}
+
+	data, err := files.ReadFile(fmt.Sprintf("testdata/%s", *filename))
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	one, two, err := problems.Solve(data)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("solution one: %d\nsolution two: %d\n", one, two)
+}

day-16/go.mod

@@ -0,0 +1,7 @@
+module github.com/onyx-and-iris/aoc2024/day-16
+
+go 1.23.3
+
+require github.com/sirupsen/logrus v1.9.3
+
+require golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 // indirect

day-16/go.sum

@@ -0,0 +1,15 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
+github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

day-16/internal/one/graph.go

@@ -0,0 +1,100 @@
+package one
+
+import (
+	hp "container/heap"
+	"errors"
+	"math"
+	"slices"
+	"strings"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const turnCost int = 1000
+
+type graph struct {
+	start node
+	end   node
+	data  []string
+}
+
+func newGraph() *graph {
+	return &graph{}
+}
+
+func (g *graph) String() string {
+	return strings.Join(g.data, "\n")
+}
+
+func (g *graph) valueAt(n node) rune {
+	return rune(g.data[n.y][n.x])
+}
+
+func (g *graph) dijkstra() (int, error) {
+	heap := newHeap()
+	hp.Push(heap, move{g.start, 0})
+	visited := make(map[node]struct{})
+	costs := make(map[node]int)
+	prev := make(map[node]node)
+
+	for heap.Len() > 0 {
+		current := hp.Pop(heap).(move)
+
+		if current.node.coords == g.end.coords {
+			log.Debugf("\n%s\n", g.debug(prev, costs))
+			return costs[g.end], nil
+		}
+
+		if _, ok := visited[current.node]; ok {
+			continue
+		}
+		visited[current.node] = struct{}{}
+
+		for _, n := range neighbours(current.node) {
+			if g.valueAt(n) == '#' {
+				continue
+			}
+
+			next_cost := current.cost + 1
+			if n.direction != current.node.direction {
+				next_cost += turnCost
+			}
+
+			_, ok := costs[n]
+			if !ok {
+				costs[n] = math.MaxInt
+			}
+
+			if next_cost < costs[n] {
+				costs[n] = next_cost
+				prev[n] = current.node
+				hp.Push(heap, move{n, next_cost})
+			}
+		}
+	}
+
+	return 0, errors.New("unable to get shortest path cost")
+}
+
+func (g *graph) debug(prev map[node]node, costs map[node]int) string {
+	path := []node{g.end}
+
+	node := prev[g.end]
+	for node != g.start {
+		path = append(path, prev[node])
+		node = prev[node]
+	}
+
+	temp := slices.Clone(g.data)
+	for _, node := range path {
+		if g.valueAt(node) == 'S' || g.valueAt(node) == 'E' {
+			continue
+		}
+		temp[node.y] = replaceAtIndex(temp[node.y], []rune{'^', '>', 'v', '<'}[node.direction], node.x)
+	}
+
+	log.Debugf("len of shortest path: %d", len(path))
+	log.Debugf("cost of shortest path: %d", costs[g.end])
+
+	return strings.Join(temp, "\n")
+}

day-16/internal/one/heap.go

@@ -0,0 +1,31 @@
+package one
+
+type minHeap []move
+
+func newHeap() *minHeap {
+	return &minHeap{}
+}
+
+func (h minHeap) Len() int {
+	return len(h)
+}
+
+func (h minHeap) Less(i, j int) bool {
+	return h[i].cost < h[j].cost
+}
+
+func (h minHeap) Swap(i, j int) {
+	h[i], h[j] = h[j], h[i]
+}
+
+func (h *minHeap) Push(x interface{}) {
+	*h = append(*h, x.(move))
+}
+
+func (h *minHeap) Pop() interface{} {
+	old := *h
+	n := len(old)
+	x := old[n-1]
+	*h = old[:n-1]
+	return x
+}

day-16/internal/one/move.go

@@ -0,0 +1,6 @@
+package one
+
+type move struct {
+	node node
+	cost int
+}

day-16/internal/one/neighbours.go

@@ -0,0 +1,32 @@
+package one
+
+func neighbours(p node) [3]node {
+	switch p.direction {
+	case N:
+		return [3]node{
+			newNode(p.x, p.y-1, N),
+			newNode(p.x-1, p.y, W),
+			newNode(p.x+1, p.y, E),
+		}
+	case E:
+		return [3]node{
+			newNode(p.x+1, p.y, E),
+			newNode(p.x, p.y-1, N),
+			newNode(p.x, p.y+1, S),
+		}
+	case S:
+		return [3]node{
+			newNode(p.x, p.y+1, S),
+			newNode(p.x-1, p.y, W),
+			newNode(p.x+1, p.y, E),
+		}
+	case W:
+		return [3]node{
+			newNode(p.x-1, p.y, W),
+			newNode(p.x, p.y+1, S),
+			newNode(p.x, p.y-1, N),
+		}
+	default:
+		return [3]node{}
+	}
+}

day-16/internal/one/node.go

@@ -0,0 +1,24 @@
+package one
+
+type direction int
+
+const (
+	N direction = iota
+	E
+	S
+	W
+)
+
+type coords struct {
+	x int
+	y int
+}
+
+type node struct {
+	coords
+	direction direction
+}
+
+func newNode(x, y int, dir direction) node {
+	return node{coords{x, y}, dir}
+}

day-16/internal/one/solve.go

@@ -0,0 +1,20 @@
+package one
+
+import (
+	"bytes"
+)
+
+func Solve(buf []byte) (int, error) {
+	r := bytes.NewReader(buf)
+	graph, err := parseLines(r)
+	if err != nil {
+		return 0, err
+	}
+
+	lowestCost, err := graph.dijkstra()
+	if err != nil {
+		return 0, err
+	}
+
+	return lowestCost, nil
+}

day-16/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-16/internal/one/util.go

@@ -0,0 +1,52 @@
+package one
+
+import (
+	"bufio"
+	"io"
+	"strings"
+)
+
+func parseLines(r io.Reader) (*graph, error) {
+	graph := newGraph()
+
+	var linecount int
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		r, indx := indxForAny(line, []rune{'S', 'E'})
+		if indx != -1 {
+			if r == 'S' {
+				graph.start = newNode(indx, linecount, E)
+			} else {
+				graph.end = newNode(indx, linecount, 0)
+			}
+		}
+
+		graph.data = append(graph.data, line)
+
+		linecount++
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	return graph, nil
+}
+
+func indxForAny(s string, runes []rune) (rune, int) {
+	for _, r := range runes {
+		indx := strings.Index(s, string(r))
+		if indx != -1 {
+			return r, indx
+		}
+	}
+	return 0, -1
+}
+
+func replaceAtIndex(s string, r rune, i int) string {
+	out := []rune(s)
+	out[i] = r
+	return string(out)
+}

day-16/makefile

@@ -0,0 +1,30 @@
+program = day-16
+
+GO = go
+SRC_DIR := src
+BIN_DIR := bin
+
+EXE := $(BIN_DIR)/$(program)
+
+.DEFAULT_GOAL := build
+
+.PHONY: fmt vet build bench clean
+fmt:        
+	$(GO) fmt ./...
+
+vet: fmt        
+	$(GO) vet ./...
+
+build: vet | $(BIN_DIR)
+	$(GO) build -o $(EXE) ./$(SRC_DIR)
+
+bench:
+	$(GO) test ./internal/one/ -bench=. > internal/one/benchmark
+	$(GO) test ./internal/two/ -bench=. > internal/two/benchmark
+	$(GO) test . -count=10 -bench=. > benchmark
+
+$(BIN_DIR):
+	@mkdir -p $@
+
+clean:
+	@rm -rv $(BIN_DIR)

day-16/solve.go

@@ -0,0 +1,20 @@
+package name
+
+import (
+	"github.com/onyx-and-iris/aoc2024/day-16/internal/one"
+	"github.com/onyx-and-iris/aoc2024/day-16/internal/two"
+)
+
+func Solve(buf []byte) (int, int, error) {
+	answerOne, err := one.Solve(buf)
+	if err != nil {
+		return 0, 0, err
+	}
+
+	answerTwo, err := two.Solve(buf)
+	if err != nil {
+		return 0, 0, err
+	}
+
+	return answerOne, answerTwo, nil
+}