Day 05. solutions

data.go

@@ -15,3 +15,6 @@ var Day03Data string
 
 //go:embed day_04/data.txt
 var Day04Data string
+
+//go:embed day_05/data.txt
+var Day05Data string

day_05/example_data.txt

@@ -0,0 +1,28 @@
+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

day_05/solution.go

@@ -0,0 +1,123 @@
+package day_05
+
+import (
+	"fmt"
+	"slices"
+	"strconv"
+	"strings"
+)
+
+type Rules map[int][]int
+type Manual []int
+
+// task:https://adventofcode.com/2024/day/5
+// short summary - count valid columns
+func SolveBasic(input string) int {
+	manuals, rules := loadManualAndRules(input)
+
+	sum := 0
+	for _, manual := range manuals {
+		if isManualValid(manual, rules) {
+			sum += manual[len(manual)/2]
+		}
+	}
+	return sum
+}
+
+// task:https://adventofcode.com/2024/day/5#part2
+// short summary - fix and count invalid columns
+func SolveComplex(input string) int {
+	manuals, rules := loadManualAndRules(input)
+
+	sum := 0
+	for _, manual := range manuals {
+		if !isManualValid(manual, rules) {
+			manual = fixManual(manual, rules)
+			sum += manual[len(manual)/2]
+		}
+	}
+	return sum
+}
+
+func fixManual(manual Manual, rules Rules) Manual {
+	for {
+		index := violationIndex(manual, rules)
+		if index == -1 {
+			return manual
+		}
+		violation := manual[index]
+		manual = slices.Delete(manual, index, index+1)
+		for i := 0; i < len(manual); i++ {
+			if values, present := rules[manual[i]]; present {
+				if slices.Contains(values, violation) {
+					manual = slices.Insert(manual, i, violation)
+					break
+				}
+			}
+		}
+	}
+}
+
+// helper methods
+
+func isManualValid(manual Manual, rules Rules) bool {
+	return violationIndex(manual, rules) == -1
+}
+
+func violationIndex(manual Manual, rules Rules) int {
+	illegalValues := []int{}
+	for i, num := range manual {
+		if slices.Contains(illegalValues, num) {
+			return i
+		}
+		if _, contains := rules[num]; contains {
+			illegalValues = append(illegalValues, rules[num]...)
+		}
+	}
+	return -1
+}
+
+func loadManualAndRules(input string) ([]Manual, Rules) {
+	substrings := strings.Split(input, "\n\n")
+
+	rules := loadRules(substrings[0])
+	manuals := loadManuals(substrings[1])
+
+	return manuals, rules
+}
+
+func loadManuals(s string) []Manual {
+	var manuals []Manual
+	for _, line := range strings.Split(s, "\n") {
+		manuals = append(manuals, loadManual(line))
+	}
+	return manuals
+}
+
+func loadManual(line string) []int {
+	var manual Manual
+	for _, value := range strings.Split(line, ",") {
+		manual = append(manual, must(strconv.Atoi(value)))
+	}
+	return manual
+}
+
+func must(val int, err error) int {
+	if err != nil {
+		panic(err)
+	}
+	return val
+}
+
+func loadRules(s string) Rules {
+	rules := map[int][]int{}
+	for _, line := range strings.Split(s, "\n") {
+		var k, v int
+		_, err := fmt.Sscanf(line, "%d|%d", &k, &v)
+		if err != nil {
+			panic(err)
+		}
+		rules[v] = append(rules[v], k)
+	}
+	return rules
+}

day_05/solution_test.go

@@ -0,0 +1,24 @@
+package day_05_test
+
+import (
+	"advent_of_code_2024/day_05"
+	_ "embed"
+	"testing"
+)
+
+//go:embed example_data.txt
+var ExampleData string
+
+func TestBasicSolutionExample(t *testing.T) {
+	result := day_05.SolveBasic(ExampleData)
+	if result != 143 {
+		t.Fatalf("Expected 143 received %d", result)
+	}
+}
+
+func TestComplexSolutionExample(t *testing.T) {
+	result := day_05.SolveComplex(ExampleData)
+	if result != 123 {
+		t.Fatalf("Expected 123 received %d", result)
+	}
+}

main.go

@@ -5,6 +5,7 @@ import (
 	"advent_of_code_2024/day_02"
 	"advent_of_code_2024/day_03"
 	"advent_of_code_2024/day_04"
+	"advent_of_code_2024/day_05"
 	_ "embed"
 	"fmt"
 	"os"
@@ -29,7 +30,11 @@ func main() {
 	case "04-basic":
 		fmt.Printf("Day 04. Basic: %d\n", day_04.SolveBasic(Day04Data)) // 2560
 	case "04-complex":
-		fmt.Printf("Day 04. Complex: %d\n", day_04.SolveComplex(Day04Data)) // 63013756
+		fmt.Printf("Day 04. Complex: %d\n", day_04.SolveComplex(Day04Data)) // 1980
+	case "05-basic":
+		fmt.Printf("Day 05. Basic: %d\n", day_05.SolveBasic(Day05Data)) // 2560
+	case "05-complex":
+		fmt.Printf("Day 05. Complex: %d\n", day_05.SolveComplex(Day05Data)) // 63013756
 	}
 }