Solve 2024 day 2 in go

2024/go/day-02/main.go

@@ -0,0 +1,97 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func readInput() ([][]int, error) {
+	content, err := os.ReadFile("input")
+	if err != nil {
+		return nil, err
+	}
+
+	lines := strings.Split(strings.TrimSpace(string(content)), "\n")
+	var reports [][]int
+
+	for _, line := range lines {
+		parts := strings.Fields(line)
+		levels := make([]int, len(parts))
+
+		for i, part := range parts {
+			levels[i], _ = strconv.Atoi(part)
+		}
+
+		reports = append(reports, levels)
+	}
+
+	return reports, nil
+}
+
+func isSafeReport(levels []int) (bool, int) {
+	isIncreasing := levels[0] < levels[len(levels)-1]
+
+	for i := 1; i < len(levels); i++ {
+		diff := levels[i] - levels[i-1]
+
+		if (isIncreasing && (diff <= 0 || diff > 3)) || (!isIncreasing && (diff >= 0 || diff < -3)) {
+			return false, i
+		}
+	}
+
+	return true, -1
+}
+
+func countSafeReports(reports [][]int) int {
+	var count int
+
+	for _, levels := range reports {
+		isSafe, _ := isSafeReport(levels)
+		if isSafe {
+			count++
+		}
+	}
+
+	return count
+}
+
+func countDampenedSafeReports(reports [][]int) int {
+	var count int
+
+	for _, levels := range reports {
+		isSafe, unsafeIndex := isSafeReport(levels)
+		if isSafe {
+			count++
+			continue
+		}
+
+		for i := unsafeIndex; i >= unsafeIndex-1 && i >= 0; i-- {
+			var dampenedLevels []int
+			dampenedLevels = append(dampenedLevels, levels[:i]...)
+			dampenedLevels = append(dampenedLevels, levels[i+1:]...)
+
+			isSafe, _ = isSafeReport(dampenedLevels)
+			if isSafe {
+				count++
+				break
+			}
+		}
+	}
+
+	return count
+}
+
+func main() {
+	reports, err := readInput()
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	// Part one
+	fmt.Println("Number of safe reports:", countSafeReports(reports))
+	// Part two
+	fmt.Println("Number of dampened safe reports:", countDampenedSafeReports(reports))
+}