Add solution day 22 part 1

terminalnode · terminalnode · commit 71a8bc7a32ef · 2024-12-22T13:24:24.000+01:00
diff --git a/README.md b/README.md
@@ -54,7 +54,7 @@ automatically rebuilt and redeployed every time the `common` module or their own
 | 06  | ⭐ ⭐      | 19  | ⭐ ⭐      |
 | 07  | ⭐ ⭐      | 20  | ⭐ ⭐      |
 | 08  | ⭐ ⭐      | 21  |          |
-| 09  | ⭐ ⭐      | 22  |          |
+| 09  | ⭐ ⭐      | 22  | ⭐        |
 | 10  | ⭐ ⭐      | 23  |          |
 | 11  | ⭐ ⭐      | 24  |          |
 | 12  | ⭐ ⭐      | 25  |          |
diff --git a/solutions/day22/main.go b/solutions/day22/main.go
@@ -1,9 +1,58 @@
 package main
 
 import (
+	"fmt"
 	"github.com/terminalnode/adventofcode2024/common"
+	"strconv"
+	"strings"
 )
 
 func main() {
-	common.Setup(22, nil, nil)
+	common.Setup(22, part1, nil)
+}
+
+func part1(
+	input string,
+) string {
+	secrets, err := parse(input)
+	if err != nil {
+		return fmt.Sprintf("Failed to parse input: %v", err)
+	}
+
+	sum := 0
+	for _, secret := range secrets {
+		for n := 0; n < 2000; n++ {
+			secret = evolveSecretNumber(secret)
+		}
+		sum += secret
+	}
+
+	return fmt.Sprintf("Sum of all secret numbers after 2k rounds: %d", sum)
+}
+
+func parse(
+	input string,
+) ([]int, error) {
+	lines := strings.Split(input, "\n")
+	numbers := make([]int, 0, len(lines))
+	for _, l := range lines {
+		n, err := strconv.ParseInt(l, 10, 0)
+		if err != nil {
+			return numbers, err
+		}
+		numbers = append(numbers, int(n))
+	}
+	return numbers, nil
+}
+
+func evolveSecretNumber(
+	secretNumber int,
+) int {
+	secretNumber = pruneNumber((secretNumber * 64) ^ secretNumber)
+	secretNumber = pruneNumber((secretNumber / 32) ^ secretNumber)
+	return pruneNumber((secretNumber * 2048) ^ secretNumber)
+}
+
+func pruneNumber(n int) int {
+	return n % 16777216
 }
