Day02

2024/gareth/day02/day02.go

@@ -0,0 +1,76 @@
+package day02
+
+import (
+	"math"
+	"strconv"
+	"strings"
+)
+
+func Part1(input string) int {
+	total := 0
+	lines := strings.Split(input, "\n")
+	for _, line := range lines {
+		var report []int
+		nums := strings.Fields(line)
+		for _, num := range nums {
+			intnum, _ := strconv.Atoi(num)
+			report = append(report, int(intnum))
+		}
+		if isSafe(report) {
+			total++
+		}
+	}
+	return total
+}
+
+func Part2(input string) int {
+	total := 0
+	lines := strings.Split(input, "\n")
+	for _, line := range lines {
+		var report []int
+		nums := strings.Fields(line)
+		for _, num := range nums {
+			intnum, _ := strconv.Atoi(num)
+			report = append(report, int(intnum))
+		}
+		if isSafeWithDampener(report) {
+			total++
+		}
+	}
+	return total
+}
+
+func isSafe(report []int) bool {
+	increasing := report[1] > report[0]
+	decreasing := report[1] < report[0]
+
+	for i := 1; i < len(report); i++ {
+		diff := report[i] - report[i-1]
+		absDiff := int(math.Abs(float64(diff)))
+
+		if absDiff < 1 || absDiff > 3 {
+			return false
+		}
+
+		if (diff > 0 && !increasing) || (diff < 0 && !decreasing) {
+			return false
+		}
+	}
+
+	return true
+}
+
+func isSafeWithDampener(report []int) bool {
+	if isSafe(report) {
+		return true
+	}
+
+	for i := 0; i < len(report); i++ {
+		modifiedReport := append(report[:i], report[i+1:]...)
+		if isSafe(modifiedReport) {
+			return true
+		}
+	}
+
+	return false
+}