1 files changed, 25 insertions(+), 50 deletions(-)

M advent_of_code/2022/day13.go

@@ 14,66 14,44 @@ type listOrInt struct {
 	lst    []listOrInt
 }
 
-func (n listOrInt) String() string {
-	s := ""
-	if n.isList {
-		s += "["
-		for i, e := range n.lst {
-			s += e.String()
-			if i+1 < len(n.lst) {
-				s += ","
-			}
-		}
-		s += "]"
-	} else {
-		s = fmt.Sprintf("%d", n.num)
-	}
-	return s
-}
-
-func readList(s string, start int) (listOrInt, int) {
+func readList(s string, mark int) (listOrInt, int) {
 	isList, num, lst := false, 0, []listOrInt{}
-	if s[start] == byte('[') {
+	if s[mark] == byte('[') {
 		isList = true
-		start++
-		for s[start] != byte(']') {
-			if s[start] == byte(',') {
-				start++
+		mark++
+		for s[mark] != byte(']') {
+			if s[mark] == byte(',') {
+				mark++
 			}
-			next, end := readList(s, start)
+			next, end := readList(s, mark)
 			lst = append(lst, next)
-			start = end
+			mark = end
 		}
-		start++
+		mark++
 	} else {
-		i := start
+		i := mark
 		for ; s[i] != byte(',') && s[i] != byte(']'); i++ {
 		}
-		if val, err := strconv.Atoi(s[start:i]); err == nil {
+		if val, err := strconv.Atoi(s[mark:i]); err == nil {
 			num = val
 		} else {
 			panic(err)
 		}
-		start = i
+		mark = i
 	}
-	return listOrInt{isList, num, lst}, start
+	return listOrInt{isList, num, lst}, mark
 }
 
 func compare(left listOrInt, right listOrInt) int {
 	if !left.isList && !right.isList {
 		return left.num - right.num
 	} else if left.isList && right.isList {
-		for i := 0; i < len(left.lst) || i < len(right.lst); i++ {
-			if i < len(left.lst) && i < len(right.lst) {
-				if x := compare(left.lst[i], right.lst[i]); x != 0 {
-					return x
-				}
-			} else if i >= len(left.lst) && i < len(right.lst) {
-				return -1
-			} else if i < len(left.lst) && i >= len(right.lst) {
-				return 1
+		for i := 0; i < len(left.lst) && i < len(right.lst); i++ {
+			if x := compare(left.lst[i], right.lst[i]); x != 0 {
+				return x
 			}
 		}
+		return len(left.lst) - len(right.lst)
 	} else if left.isList && !right.isList {
 		if x := compare(left, listOrInt{true, 0, []listOrInt{right}}); x != 0 {
 			return x


@@ 100,10 78,9 @@ func main() {
 		panic(err)
 	}
 	lines := strings.Split(string(input), "\n")
-	part1 := 0
+	part1, part2 := 0, []int{1, 1}
 	div2, _ := readList("[[2]]", 0)
 	div6, _ := readList("[[6]]", 0)
-	part2 := []int{1, 1}
 	for i := 0; i < len(lines); i += 3 {
 		index, a, b := (i+1)/3+1, i, i+1
 		left, _ := readList(lines[a], 0)


@@ 111,15 88,13 @@ func main() {
 		if compare(left, right) < 1 {
 			part1 += index
 		}
-		if compare(left, div2) < 1 {
-			part2[0]++
-		} else if compare(left, div6) < 1 {
-			part2[1]++
-		}
-		if compare(right, div2) < 1 {
-			part2[0]++
-		} else if compare(right, div6) < 1 {
-			part2[1]++
+		listOrInts := []listOrInt{left, right}
+		for _, loi := range listOrInts {
+			if compare(loi, div2) < 1 {
+				part2[0]++
+			} else if compare(loi, div6) < 1 {
+				part2[1]++
+			}
 		}
 	}