test: add unit test for part one

internal/2025/DayEleven/code.go

@@ -2,6 +2,7 @@ package dayeleven
 
 import (
 	"os"
+	"slices"
 	"strings"
 
 	"advent-of-code/internal/registry"
@@ -16,10 +17,137 @@ func ParseInput(filepath string) []string {
 	return strings.Split(string(content), "\n")
 }
 
-func PartOne(data []string) int {
+func buildGraph(data []string) map[string][]string {
+	graph := make(map[string][]string)
+
+	for _, line := range data {
+		device, outputsStr, _ := strings.Cut(line, ": ")
+		graph[device] = strings.Fields(outputsStr)
+	}
+
+	return graph
+}
+
+func hasCycle(graph map[string][]string) bool {
+	const (
+		unvisited = iota
+		visiting
+		visited
+	)
+
+	state := make(map[string]uint8)
+
+	var dfs func(node string) bool
+	dfs = func(node string) bool {
+		switch state[node] {
+		case visiting:
+			return true
+		case visited:
+			return false
+		}
+
+		state[node] = visiting
+		if slices.ContainsFunc(graph[node], dfs) {
+			return true
+		}
+		state[node] = visited
+		return false
+	}
+
+	for node := range graph {
+		if state[node] == unvisited {
+			if dfs(node) {
+				return true
+			}
+		}
+	}
+
+	return false
+}
+
+func countPaths(graph map[string][]string, start, end string, requiredNodes map[string]bool) int {
+	requiredIndex := make(map[string]uint)
+	var targetMask uint
+	for node := range requiredNodes {
+		requiredIndex[node] = uint(len(requiredIndex))
+		targetMask |= 1 << requiredIndex[node]
+	}
+
+	if hasCycle(graph) {
+		var dfs func(node string, visited map[string]bool, seenMask uint) int
+		dfs = func(node string, visited map[string]bool, seenMask uint) int {
+			if node == end {
+				if seenMask != targetMask {
 					return 0
 				}
+				return 1
+			}
+
+			if idx, ok := requiredIndex[node]; ok {
+				seenMask |= 1 << idx
+			}
+
+			visited[node] = true
+			defer delete(visited, node)
+
+			count := 0
+			for _, neighbor := range graph[node] {
+				if !visited[neighbor] {
+					count += dfs(neighbor, visited, seenMask)
+				}
+			}
+			return count
+		}
+
+		return dfs(start, make(map[string]bool), 0)
+	}
+
+	type key struct {
+		node string
+		mask uint
+	}
+	memo := make(map[key]int)
+
+	var dfs func(node string, seenMask uint) int
+	dfs = func(node string, seenMask uint) int {
+		if node == end {
+			if seenMask != targetMask {
+				return 0
+			}
+			return 1
+		}
+
+		if idx, ok := requiredIndex[node]; ok {
+			seenMask |= 1 << idx
+		}
+
+		state := key{node: node, mask: seenMask}
+		if cached, ok := memo[state]; ok {
+			return cached
+		}
+
+		count := 0
+		for _, neighbor := range graph[node] {
+			count += dfs(neighbor, seenMask)
+		}
+
+		memo[state] = count
+		return count
+	}
+
+	return dfs(start, 0)
+}
+
+func PartOne(data []string) int {
+	graph := buildGraph(data)
+	return countPaths(graph, "you", "out", nil)
+}
 
 func PartTwo(data []string) int {
-	return 0
+	graph := buildGraph(data)
+	requiredNodes := map[string]bool{
+		"dac": true,
+		"fft": true,
+	}
+	return countPaths(graph, "svr", "out", requiredNodes)
 }

internal/2025/DayEleven/code_test.go

@@ -2,7 +2,8 @@ package dayeleven
 
 import "testing"
 
-var testInput = []string{
+func TestPartOne(t *testing.T) {
+	testInput := []string{
 		"aaa: you hhh",
 		"you: bbb ccc",
 		"bbb: ddd eee",
@@ -14,11 +15,32 @@ var testInput = []string{
 		"hhh: ccc fff iii",
 		"iii: out",
 	}
-
-func TestPartOne(t *testing.T) {
 	expected := 5
 	got := PartOne(testInput)
 	if got != expected {
 		t.Errorf("PartOne() = %d, want %d", got, expected)
 	}
 }
+
+func TestPartTwo(t *testing.T) {
+	testInput := []string{
+		"svr: aaa bbb",
+		"aaa: fft",
+		"fft: ccc",
+		"bbb: tty",
+		"tty: ccc",
+		"ccc: ddd eee",
+		"ddd: hub",
+		"hub: fff",
+		"eee: dac",
+		"dac: fff",
+		"fff: ggg hhh",
+		"ggg: out",
+		"hhh: out",
+	}
+	expected := 2
+	got := PartTwo(testInput)
+	if got != expected {
+		t.Errorf("PartTwo() = %d, want %d", got, expected)
+	}
+}

internal/2025/DayTwelve/code.go

@@ -0,0 +1,17 @@
+package daytwelve
+
+import (
+	"os"
+	"strings"
+
+	"advent-of-code/internal/registry"
+)
+
+func init() {
+	registry.Register("2025D12", ParseInput, PartOne, PartTwo)
+}
+
+func ParseInput(filepath string) []string {
+	content, _ := os.ReadFile(filepath)
+	return strings.Split(string(content), "\n")
+}

internal/2025/DayTwelve/code_test.go

@@ -0,0 +1,47 @@
+package daytwelve
+
+import "testing"
+
+var testInput = []string{
+	"0:",
+	"###",
+	"##.",
+	"##.",
+	"",
+	"1:",
+	"###",
+	"##.",
+	".##",
+	"",
+	"2:",
+	".##",
+	"###",
+	"##.",
+	"",
+	"3:",
+	"##.",
+	"###",
+	"##.",
+	"",
+	"4:",
+	"###",
+	"#..",
+	"###",
+	"",
+	"5:",
+	"###",
+	".#.",
+	"###",
+	"",
+	"4x4: 0 0 0 0 2 0",
+	"12x5: 1 0 1 0 2 2",
+	"12x5: 1 0 1 0 3 2",
+}
+
+func TestPartOne(t *testing.T) {
+	expected := 2
+	got := PartOne(testInput)
+	if got != expected {
+		t.Errorf("PartOne() = %d, want %d", got, expected)
+	}
+}

internal/2025/register.go

@@ -11,5 +11,6 @@ import (
 	_ "advent-of-code/internal/2025/DaySix"
 	_ "advent-of-code/internal/2025/DayTen"
 	_ "advent-of-code/internal/2025/DayThree"
+	_ "advent-of-code/internal/2025/DayTwelve"
 	_ "advent-of-code/internal/2025/DayTwo"
 )