d12

d12/common.go

@@ -0,0 +1,65 @@
+package d12
+
+import (
+	"strings"
+)
+
+type caveMap map[string][]string
+
+func getLines(in string) []string {
+	return strings.Split(strings.TrimSpace(in), "\n")
+}
+
+func getPairs(lines []string) [][]string {
+	pairs := [][]string{}
+
+	for _, line := range lines {
+		pairs = append(pairs, strings.Split(line, "-"))
+	}
+
+	return pairs
+}
+
+func createMap(paths [][]string) caveMap {
+	caveMap := make(map[string][]string)
+
+	for _, path := range paths {
+		left := path[0]
+		right := path[1]
+
+		caveMap[left] = append(caveMap[left], right)
+		caveMap[right] = append(caveMap[right], left)
+	}
+
+	return caveMap
+}
+
+func countPaths(caveMap caveMap, key string, visited map[string]int, duplicate bool) int {
+	count := 0
+
+	if key == "end" {
+		return 1
+	}
+
+	if visited[key] > 0 {
+		if key == "start" {
+			return 0
+		}
+
+		if strings.ToUpper(key) != key {
+			if duplicate {
+				return 0
+			} else {
+				duplicate = true
+			}
+		}
+	}
+
+	visited[key]++
+	for _, path := range caveMap[key] {
+		count += countPaths(caveMap, path, visited, duplicate)
+	}
+	visited[key]--
+
+	return count
+}

d12/d12_test.go

@@ -0,0 +1,31 @@
+package d12
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestP1(t *testing.T) {
+	in := `start-A
+start-b
+A-c
+A-b
+b-d
+A-end
+b-end`
+
+	assert.EqualValues(t, 10, P1(in))
+}
+
+func TestP2(t *testing.T) {
+	in := `start-A
+start-b
+A-c
+A-b
+b-d
+A-end
+b-end`
+
+	assert.EqualValues(t, 36, P2(in))
+}

d12/p1.go

@@ -0,0 +1,5 @@
+package d12
+
+func P1(input string) int {
+	return countPaths(createMap(getPairs(getLines(input))), "start", make(map[string]int), true)
+}

d12/p2.go

@@ -0,0 +1,5 @@
+package d12
+
+func P2(input string) int {
+	return countPaths(createMap(getPairs(getLines(input))), "start", make(map[string]int), false)
+}

main.go

@@ -10,6 +10,7 @@ import (
 	"github.com/fotonmoton/aoc2021/d1"
 	"github.com/fotonmoton/aoc2021/d10"
 	"github.com/fotonmoton/aoc2021/d11"
+	"github.com/fotonmoton/aoc2021/d12"
 	"github.com/fotonmoton/aoc2021/d2"
 	"github.com/fotonmoton/aoc2021/d3"
 	"github.com/fotonmoton/aoc2021/d4"
@@ -52,4 +53,6 @@ func main() {
 	fmt.Printf("day 10 part 2: %v\n", d10.P2(client.Day(10)))
 	fmt.Printf("day 11: %v\n", d11.P1(client.Day(11)))
 	fmt.Printf("day 11 part 2: %v\n", d11.P2(client.Day(11)))
+	fmt.Printf("day 12: %v\n", d12.P1(client.Day(12)))
+	fmt.Printf("day 12 part 2: %v\n", d12.P2(client.Day(12)))
 }