2022 Day 6 Complete!

2022/day06/main.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"fmt"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToString()
+	fmt.Println("# Part 1")
+	fmt.Printf("First Start of Packet @ %d\n", findFirstStartOfPacket(inp))
+	fmt.Println("")
+	fmt.Println("# Part 2")
+	fmt.Printf("First Start of Message @ %d\n", findFirstStartOfMessage(inp))
+}
+
+func findFirstStartOfPacket(inp string) int {
+	return findFirstWithXUnique(inp, 4)
+}
+
+func findFirstStartOfMessage(inp string) int {
+	return findFirstWithXUnique(inp, 14)
+}
+
+func findFirstWithXUnique(inp string, x int) int {
+	for i := range inp {
+		if i < x {
+			continue
+		}
+		if findUniqueCountBefore(inp, i) >= x {
+			return i + 1
+		}
+	}
+	return -1
+}
+
+func findUniqueCountBefore(inp string, pos int) int {
+	if len(inp) < pos {
+		return -1
+	}
+	counts := make(map[byte]int)
+	for i := pos; i >= 0; i-- {
+		if _, ok := counts[inp[i]]; !ok {
+			counts[inp[i]]++
+		} else {
+			return len(counts)
+		}
+	}
+	return pos
+}