implement using custom sort function on an update struct

rerun benchmarks

day-05/internal/util/util.go

@@ -3,47 +3,51 @@ package util
 import (
 	"bufio"
 	"io"
-	"log"
 	"strconv"
 	"strings"
+
+	"github.com/onyx-and-iris/aoc2024/day-05/internal/update"
 )
 
-func MustConv(s string) int {
+func ParseLines(r io.Reader) ([]update.Update, map[int][]int, error) {
+	var updates []update.Update
+	orderings := make(map[int][]int, 0)
+
+	var inUpdates bool
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if len(line) == 0 {
+			inUpdates = true
+			continue
+		}
+
+		if inUpdates {
+			var update update.Update
+			for _, n := range strings.Split(line, ",") {
+				update.Pages = append(update.Pages, mustConv(n))
+			}
+			updates = append(updates, update)
+		} else {
+			left, right := func() (int, int) {
+				x := strings.Split(line, "|")
+				return mustConv(x[0]), mustConv(x[1])
+			}()
+			orderings[left] = append(orderings[left], right)
+		}
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, nil, err
+	}
+
+	return updates, orderings, nil
+}
+
+func mustConv(s string) int {
 	n, err := strconv.Atoi(s)
 	if err != nil {
 		panic(err)
 	}
 	return n
 }
-
-func ParseLines(r io.Reader) ([][][]int, error) {
-	data := make([][][]int, 2)
-
-	filter := func(r rune) bool {
-		return r == '|' || r == ','
-	}
-
-	buf, err := io.ReadAll(r)
-	if err != nil {
-		log.Fatal(err)
-	}
-	parts := strings.Split(string(buf), "\n\n")
-
-	for i, part := range parts {
-		scanner := bufio.NewScanner(strings.NewReader(part))
-		for scanner.Scan() {
-			filtered := strings.FieldsFunc(scanner.Text(), filter)
-			var nums []int
-			for _, n := range filtered {
-				nums = append(nums, MustConv(n))
-			}
-			data[i] = append(data[i], nums)
-		}
-
-		if err := scanner.Err(); err != nil {
-			return nil, err
-		}
-	}
-
-	return data, nil
-}