2024 Day 02 Complete!

2024/day02/main.go

@@ -0,0 +1,110 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	helpers "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := helpers.StdinToStringSlice()
+	part1(inp)
+	part2(inp)
+}
+
+func part1(inp []string) {
+	var ret int
+	for _, report := range inp {
+		wrk := cleanReport(report)
+		if testReport(wrk) {
+			ret++
+		}
+	}
+	fmt.Println("# Part 1")
+	fmt.Printf("%d reports are safe\n", ret)
+}
+
+func part2(inp []string) {
+	var ret int
+	for _, report := range inp {
+		wrk := cleanReport(report)
+		if testReport(wrk) {
+			ret++
+		} else {
+			if testDampenedReport(wrk) {
+				ret++
+			}
+		}
+	}
+	fmt.Println("# Part 2")
+	fmt.Printf("%d reports are safe\n", ret)
+}
+
+func cleanReport(inp string) []int {
+	var ret []int
+	wrk := strings.Split(inp, " ")
+	for i := range wrk {
+		w, err := strconv.Atoi(wrk[i])
+		if err != nil {
+			panic(err)
+		}
+		ret = append(ret, w)
+	}
+	return ret
+}
+
+func testReport(report []int) bool {
+	var prev int
+	var dir int
+	for idx, val := range report {
+		switch idx {
+		case 0:
+			prev = val
+		case 1:
+			if val < prev {
+				dir = -1
+			} else {
+				dir = 1
+			}
+			fallthrough
+		default:
+			if (val < prev && dir == 1) || (val > prev && dir == -1) {
+				return false
+			}
+			if dir == 1 {
+				if (val-prev < 1) || (val-prev > 3) {
+					return false
+				}
+			} else {
+				if (prev-val < 1) || (prev-val > 3) {
+					return false
+				}
+			}
+			prev = val
+		}
+	}
+	return true
+}
+
+func testDampenedReport(report []int) bool {
+	for i := range report {
+		wrk := removeIdx(report, i)
+		if testReport(wrk) {
+			return true
+		}
+	}
+	return false
+}
+
+func removeIdx(a []int, idx int) []int {
+	var ret []int
+	for i := range a {
+		if i == idx {
+			continue
+		}
+		ret = append(ret, a[i])
+	}
+	return ret
+}