complete day 5

2024/day05.go

@@ -0,0 +1,99 @@
+package adventoc2024
+
+import (
+	"bufio"
+	"io"
+	"slices"
+	"sort"
+	"strings"
+)
+
+type Day5 struct{}
+
+func (d Day5) Part1(r io.Reader) string {
+	s := bufio.NewScanner(r)
+	before := make(map[int][]int, 100)
+	var sum int
+
+	var updates bool
+Scan:
+	for s.Scan() {
+		updates = updates || s.Text() == ""
+
+		if !updates {
+			s1, s2, _ := strings.Cut(s.Text(), "|")
+			i, j := atoi(s1), atoi(s2)
+			before[j] = append(before[j], i)
+		} else if s.Text() != "" {
+			pages := strings.Split(s.Text(), ",")
+			var v1, v2 int
+			for i := range pages {
+				v1 = atoi(pages[i])
+
+				for j := range pages[i+1:] {
+					v2 = atoi(pages[i+j+1])
+					for _, mustbefore := range before[v1] {
+						if mustbefore == v2 {
+							continue Scan
+						}
+					}
+				}
+			}
+			sum += atoi(pages[(len(pages)-1)/2])
+		}
+	}
+
+	return printi(sum)
+}
+
+func (d Day5) Part2(r io.Reader) string {
+	s := bufio.NewScanner(r)
+	before := make(map[int][]int, 100)
+	var sum int
+
+	var updates bool
+	for s.Scan() {
+		updates = updates || s.Text() == ""
+
+		if !updates {
+			s1, s2, _ := strings.Cut(s.Text(), "|")
+			i, j := atoi(s1), atoi(s2)
+			before[j] = append(before[j], i)
+		} else if s.Text() != "" {
+			pages := strings.Split(s.Text(), ",")
+			pageNums := make([]int, len(pages))
+			pageCopy := make([]int, len(pages))
+
+			for i := range pages {
+				pageNums[i], pageCopy[i] = atoi(pages[i]), atoi(pages[i])
+			}
+
+			sortPages(pageNums, before)
+			if !slices.Equal(pageNums, pageCopy) {
+				sum += middlePage(pageNums)
+			}
+		}
+	}
+
+	return printi(sum)
+}
+
+func sortPages(update []int, before map[int][]int) {
+	sort.Slice(update, func(i, j int) bool {
+		v1 := update[i]
+		v2 := update[j]
+
+		search := before[v1]
+		for k := range search {
+			if search[k] == v2 {
+				return false
+			}
+		}
+
+		return true
+	})
+}
+
+func middlePage(pages []int) int {
+	return pages[(len(pages)-1)/2]
+}

2024/puzzle_test.go

@@ -80,6 +80,39 @@ S.S.S.S.S.
 M.M.M.M.M.
 ..........`,
 		},
+		{
+			solver: Day5{},
+			ans1:   "143",
+			ans2:   "123",
+			inp1: `47|53
+97|13
+97|61
+97|47
+75|29
+61|13
+75|53
+29|13
+97|29
+53|29
+61|53
+97|53
+61|29
+47|13
+75|47
+97|75
+47|61
+75|61
+47|29
+75|13
+53|13
+
+75,47,61,53,29
+97,61,53,29,13
+75,29,13
+75,97,47,61,53
+61,13,29
+97,13,75,29,47`,
+		},
 	}
 
 	for i, tt := range tests {

main.go

@@ -20,6 +20,7 @@ var puzzles = map[string]puzzle{
 	"2": adventoc2024.Day2{},
 	"3": adventoc2024.Day3{},
 	"4": adventoc2024.Day4{},
+	"5": adventoc2024.Day5{},
 }
 
 func main() {