in Go, but like Ruby

Author: Robb Kidd

2022/go/day06/main.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+
+	"github.com/robbkidd/aoc2022/tools"
+)
+
+func main() {
+	input := strings.Trim(tools.Read("day06"), "\n")
+	fmt.Printf("Part 1: %v\n", scanForMarker(input, 4))
+	fmt.Printf("Part 2: %v\n", scanForMarker(input, 14))
+}
+
+func scanForMarker(buffer string, packetLength int) int {
+	lookback := packetLength - 1
+	for scan := lookback; scan < len(buffer); scan++ {
+		if packetLength == len(uniqSorted(buffer[(scan-lookback):(scan+1)])) {
+			return scan + 1
+		}
+	}
+	return -1
+}
+
+func uniqSorted(s string) string {
+	seen := struct{}{}
+	chars := make(map[rune]struct{})
+	for _, char := range s {
+		chars[char] = seen
+	}
+	var uniqRunes []rune
+	for char := range chars {
+		uniqRunes = append(uniqRunes, char)
+	}
+	sort.Slice(uniqRunes, func(i, j int) bool {
+		return i < j
+	})
+	return string(uniqRunes)
+}

2022/go/day06/main_test.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestScanForMarker(t *testing.T) {
+	testCases := []struct {
+		input                string
+		startOfPacketMarker  int
+		startOfMessageMarker int
+	}{
+		{
+			input:                "mjqjpqmgbljsphdztnvjfqwrcgsmlb",
+			startOfPacketMarker:  7,
+			startOfMessageMarker: 19,
+		},
+		{
+			input:                "bvwbjplbgvbhsrlpgdmjqwftvncz",
+			startOfPacketMarker:  5,
+			startOfMessageMarker: 23,
+		},
+		{
+			input:                "nppdvjthqldpwncqszvftbrmjlhg",
+			startOfPacketMarker:  6,
+			startOfMessageMarker: 23,
+		},
+		{
+			input:                "nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg",
+			startOfPacketMarker:  10,
+			startOfMessageMarker: 29,
+		},
+		{
+			input:                "zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw",
+			startOfPacketMarker:  11,
+			startOfMessageMarker: 26,
+		},
+	}
+	for _, tC := range testCases {
+		t.Run(tC.input, func(t *testing.T) {
+			t.Run("packet", func(t *testing.T) {
+				assert.Equal(t,
+					tC.startOfPacketMarker,
+					scanForMarker(tC.input, 4),
+					"Failed expected packet lock",
+				)
+			})
+			t.Run("message", func(t *testing.T) {
+				assert.Equal(t,
+					tC.startOfMessageMarker,
+					scanForMarker(tC.input, 14),
+					"Failed expected message lock",
+				)
+			})
+		})
+	}
+}
+
+func TestUniqSorted(t *testing.T) {
+	assert.Equal(t,
+		"abc",
+		uniqSorted("aabbccaaa"),
+	)
+}