advent2022

commit 772f53dd72502bb5a0aea7a3c9145dc7d27b6c0d
parent 4145ed6a4233b0293557e36d69eb863ba52bd100
Author: bsandro <email@bsandro.tech>
Date:   Tue,  6 Dec 2022 07:57:26 +0000

Day 06 proper solution and not the O(n^3) naive garbage I've got before

Diffstat:
M
day06/main.go
 | 
27
++++++++++++---------------

1 file changed, 12 insertions(+), 15 deletions(-)
diff --git a/day06/main.go b/day06/main.go
@@ -33,27 +33,24 @@ func day06(input_file string) {
 func checkStream(input []byte, size int) int {
 	var buf []byte
 	for i, b := range input {
-		if len(buf) == size {
-			buf = buf[1:]
+		if len(buf) > 0 {
+			has, pos := sliceHas(buf, b)
+			if has {
+				buf = buf[pos+1:]
+			} else if len(buf) == size-1 {
+				return i + 1
+			}
 		}
 		buf = append(buf, b)
-		if checkMarker(buf, size) {
-			return i+1
-		}
 	}
 	return -1
 }
 
-func checkMarker(buf []byte, size int) bool {
-	if len(buf) != size {
-		return false
-	}
-	for i:=0; i<size; i++ {
-		for j:=0; j<size; j++ {
-			if i!=j && buf[i] == buf[j] {
-				return false
-			}
+func sliceHas(buf []byte, n byte) (bool, int) {
+	for i, e := range buf {
+		if e == n {
+			return true, i
 		}
 	}
-	return true
+	return false, -1
 }