Implementation for 3b

aoc2018.go

@@ -39,7 +39,7 @@ func main() {
 	rootCmd.AddCommand(
 		day1.A, day1.B,
 		day2.A, day2.B,
-		day3.A,
+		day3.A, day3.B,
 	)
 
 	flags := rootCmd.PersistentFlags()

day3/a.go

@@ -34,6 +34,7 @@ func intMin(a, b int) int {
 }
 
 type claim struct {
+	id     int
 	top    int
 	left   int
 	width  int
@@ -50,6 +51,12 @@ func parseClaim(line string) *claim {
 
 	result := &claim{}
 
+	if id, err := strconv.Atoi(strings.TrimLeft(parts[0], "#")); err != nil {
+		panic(err)
+	} else {
+		result.id = id
+	}
+
 	if l, err := strconv.Atoi(tl[0]); err != nil {
 		panic(err)
 	} else {

day3/b.go

@@ -0,0 +1,42 @@
+package day3
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+
+	"github.com/nlowe/aoc2018/util"
+)
+
+var B = &cobra.Command{
+	Use:   "3b",
+	Short: "Day 3, Problem B",
+	Run: func(_ *cobra.Command, _ []string) {
+		fmt.Printf("Answer: %d\n", b(util.ReadInput()))
+	},
+}
+
+func b(input *util.ChallengeInput) int {
+	var claims []*claim
+
+	for line := range input.Lines() {
+		claims = append(claims, parseClaim(line))
+	}
+
+search:
+	for i := 0; i < len(claims); i++ {
+		for j := 0; j < len(claims); j++ {
+			if i == j {
+				continue
+			}
+
+			if claims[i].intersection(claims[j]) != nil {
+				continue search
+			}
+		}
+
+		return claims[i].id
+	}
+
+	panic("All claims overlap with at least one other claim")
+}

day3/b_test.go

@@ -0,0 +1,16 @@
+package day3
+
+import (
+	"testing"
+
+	"github.com/nlowe/aoc2018/util"
+	"github.com/stretchr/testify/require"
+)
+
+func TestB(t *testing.T) {
+	input := util.TestInput(`#1 @ 1,3: 4x4
+#2 @ 3,1: 4x4
+#3 @ 5,5: 2x2`)
+
+	require.Equal(t, 3, b(input))
+}