Added all code for day 22

2024/cmd/root.go

@@ -30,6 +30,7 @@ import (
 	"cpatino.com/advent-of-code/2024/day19"
 	"cpatino.com/advent-of-code/2024/day20"
 	"cpatino.com/advent-of-code/2024/day21"
+	"cpatino.com/advent-of-code/2024/day22"
 )
 
 var days = map[int]func(string) (interface{}, interface{}){
@@ -54,6 +55,7 @@ var days = map[int]func(string) (interface{}, interface{}){
 	19: day19.Run,
 	20: day20.Run,
 	21: day21.Run,
+	22: day22.Run,
 }
 
 var rootCmd = &cobra.Command{

2024/day22/day22.go

@@ -0,0 +1,134 @@
+package day22
+
+import (
+	"bufio"
+	"os"
+	"strconv"
+	"sync"
+)
+
+type SharedStore struct {
+	Store map[string]int
+	Lock  sync.Mutex
+}
+
+func secretIterator(initial int, limit int) func() (int, bool) {
+	current := initial
+	count := 0
+	return func() (int, bool) {
+		if count >= limit {
+			return -1, false
+		}
+
+		current = (current ^ (current * 64)) % 16777216
+		current = (current ^ (current / 32)) % 16777216
+		current = (current ^ (current * 2048)) % 16777216
+
+		count += 1
+		return current, true
+	}
+}
+
+func Part1(secrets []int) int {
+	sum := 0
+	for _, secret := range secrets {
+		iter := secretIterator(secret, 2000)
+
+		last := -1
+		for secret, ok := iter(); ok; secret, ok = iter() {
+			last = secret
+		}
+
+		sum += last
+	}
+
+	return sum
+}
+
+func Part2(secrets []int) int {
+	var wg sync.WaitGroup
+
+	rewards := SharedStore{Store: make(map[string]int)}
+	for _, secret := range secrets {
+		wg.Add(1)
+		go func(secret int) {
+			defer wg.Done()
+
+			iter := secretIterator(secret, 2000)
+			previousPrice := secret % 10
+
+			buyer := make(map[string]int)
+			var changes []int
+			for secret, ok := iter(); ok; secret, ok = iter() {
+				currentPrice := secret % 10
+				change := currentPrice - previousPrice
+				previousPrice = currentPrice
+
+				changes = append(changes, change)
+
+				if len(changes) > 4 {
+					changes = changes[1:]
+				}
+
+				if len(changes) == 4 {
+					key := ""
+					for _, change := range changes {
+						key += strconv.Itoa(change) + ","
+					}
+
+					if _, ok := buyer[key]; !ok {
+						buyer[key] = currentPrice
+					}
+				}
+			}
+
+			rewards.Lock.Lock()
+			defer rewards.Lock.Unlock()
+			for key, reward := range buyer {
+				rewards.Store[key] += reward
+			}
+		}(secret)
+	}
+
+	wg.Wait()
+
+	max := 0
+	for _, reward := range rewards.Store {
+		if reward > max {
+			max = reward
+		}
+	}
+
+	return max
+}
+
+func Run(filename string) (interface{}, interface{}) {
+	file, err := os.Open(filename)
+	if err != nil {
+		panic(err)
+	}
+	defer file.Close()
+
+	var secrets []int
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		number, err := strconv.Atoi(line)
+		if err != nil {
+			panic(err)
+		}
+
+		secrets = append(secrets, number)
+	}
+
+	if err := scanner.Err(); err != nil {
+		panic(err)
+	}
+
+	part1 := Part1(secrets)
+	part2 := Part2(secrets)
+
+	return part1, part2
+}

2024/day22/day22_test.go

@@ -0,0 +1,34 @@
+package day22
+
+import (
+	"os"
+	"testing"
+)
+
+type TestCase struct {
+	FileName string
+	Part1    interface{}
+	Part2    interface{}
+}
+
+func TestDay22(t *testing.T) {
+	tests := []TestCase{
+		{"test.txt", 37990510, 23},
+		{"input.txt", 19241711734, 2058},
+	}
+
+	for _, test := range tests {
+		if _, err := os.Stat(test.FileName); os.IsNotExist(err) {
+			t.Fatalf("test file does not exist: %v", test.FileName)
+		}
+
+		part1, part2 := Run(test.FileName)
+		if test.Part1 != nil && part1 != test.Part1 {
+			t.Fatalf("%s: unexpected part1:\nwant:\t%v\ngot:\t%v", test.FileName, test.Part1, part1)
+		}
+
+		if test.Part2 != nil && part2 != test.Part2 {
+			t.Fatalf("%s: unexpected part2:\nwant:\t%v\ngot:\t%v", test.FileName, test.Part2, part2)
+		}
+	}
+}

2024/day22/test.txt

@@ -0,0 +1,4 @@
+1
+2
+3
+2024