Add solution day 19 part 1

terminalnode · terminalnode · commit f07cbd98a7a5 · 2024-12-19T17:53:12.000+01:00
diff --git a/README.md b/README.md
@@ -51,7 +51,7 @@ automatically rebuilt and redeployed every time the `common` module or their own
 | 03  | ⭐ ⭐      | 16  | ⭐ 🥸     |
 | 04  | ⭐ ⭐      | 17  | ⭐ ⭐      |
 | 05  | ⭐ ⭐      | 18  | ⭐ ⭐      |
-| 06  | ⭐ ⭐      | 19  |          |
+| 06  | ⭐ ⭐      | 19  | ⭐        |
 | 07  | ⭐ ⭐      | 20  |          |
 | 08  | ⭐ ⭐      | 21  |          |
 | 09  | ⭐ ⭐      | 22  |          |
diff --git a/solutions/day19/main.go b/solutions/day19/main.go
@@ -1,9 +1,33 @@
 package main
 
 import (
+	"fmt"
 	"github.com/terminalnode/adventofcode2024/common"
+	"regexp"
+	"strings"
 )
 
 func main() {
-	common.Setup(19, nil, nil)
+	common.Setup(19, part1, nil)
+}
+
+func part1(
+	input string,
+) string {
+	p, err := parse(input)
+	if err != nil {
+		return fmt.Sprintf("Failed to parse input: %v", err)
+	}
+
+	join := strings.Join(p.available, "|")
+	r := regexp.MustCompile(fmt.Sprintf("^(%s)+$", join))
+
+	count := 0
+	for _, desired := range p.desired {
+		if r.MatchString(desired) {
+			count++
+		}
+	}
+
+	return fmt.Sprintf("%d of the %d desired designs are possible", count, len(p.desired))
 }
diff --git a/solutions/day19/parse.go b/solutions/day19/parse.go
@@ -0,0 +1,35 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+)
+
+type parsedInput struct {
+	available []string
+	desired   []string
+}
+
+func parse(
+	input string,
+) (parsedInput, error) {
+	split := strings.Split(input, "\n\n")
+	if len(split) != 2 {
+		return parsedInput{}, fmt.Errorf("expected two parts in input, got %d", len(split))
+	}
+
+	available := strings.Split(split[0], ", ")
+	if len(available) == 0 {
+		return parsedInput{}, fmt.Errorf("no available patterns found")
+	}
+
+	desired := strings.Split(split[1], "\n")
+	if len(desired) == 0 {
+		return parsedInput{}, fmt.Errorf("no desired patterns found")
+	}
+
+	return parsedInput{
+		available: available,
+		desired:   desired,
+	}, nil
+}
