Day 2a

day02/day02.go

@@ -0,0 +1,82 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type Game struct {
+	id int
+	sets []Set
+}
+
+type Set struct {
+	red int
+	green int
+	blue int
+}
+
+func parseGame(input string) Game {
+	idStr, setsStr, _ := strings.Cut(input, ": ")
+
+	var game Game
+	var err error
+
+	game.id, err = strconv.Atoi(strings.TrimPrefix(idStr, "Game "))
+
+	for i, setStr := range strings.Split(setsStr, "; ") {
+		game.sets = append(game.sets, Set{})
+		for _, colorStr := range strings.Split(setStr, ", ") {
+			if strings.HasSuffix(colorStr, " red") {
+				game.sets[i].red, err = strconv.Atoi(strings.TrimSuffix(colorStr, " red"))
+			}
+			if strings.HasSuffix(colorStr, " green") {
+				game.sets[i].green, err = strconv.Atoi(strings.TrimSuffix(colorStr, " green"))
+			}
+			if strings.HasSuffix(colorStr, " blue") {
+				game.sets[i].blue, err = strconv.Atoi(strings.TrimSuffix(colorStr, " blue"))
+			}
+		}
+	}
+
+    if err != nil {
+        panic("day02: invalid game format")
+    }
+
+	return game
+}
+
+func isGameValid(game Game) bool {
+	for _, set := range game.sets {
+		if set.red > 12 || set.green > 13 || set.blue > 14 {
+			return false
+		}
+	}
+	return true
+}
+
+func ScanFile(file *os.File) (int, error) {
+	scanner := bufio.NewScanner(file)
+	sum := 0
+    for scanner.Scan() {
+		if game := parseGame(scanner.Text()); isGameValid(game) {
+			sum += game.id
+		}
+    }
+    if err := scanner.Err(); err != nil {
+        return 0, err
+    }
+	return sum, nil
+}
+
+func main() {
+	sum, err := ScanFile(os.Stdin)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Invalid input: %s\n", err)
+		return
+	}
+	fmt.Println(sum)
+}

day02/day02_test.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"os"
+	"testing"
+)
+
+func TestScanFile(t *testing.T) {
+    cases := []struct {
+        inFile string;
+		want int;
+    }{
+        {"input1.txt", 8},
+    }
+
+    for _, c := range cases {
+		f, err := os.Open(c.inFile)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		got, err := ScanFile(f)
+		if err != nil {
+			t.Fatal(err)
+		}
+		
+		if got != c.want {
+			t.Errorf("ScanFile(%q) == %d, want %d", c.inFile, got, c.want)
+		}
+	}
+}

day02/input1.txt

@@ -0,0 +1,5 @@
+Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green