aoc_2024/three.go

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func check(e error) {
	if e != nil {
		panic(e)
	}
}

func is_safe(levels []int) bool {
	all_diffs_neg := true
	all_diffs_pos := true

	prev := levels[0]
	for i, level := range levels {
		if i == 0 {
			prev = level
			continue
		}

		diff := level - prev
		if diff > 3 || diff < -3 || diff == 0 {
			return false
		}

		all_diffs_pos = all_diffs_pos && diff > 0
		all_diffs_neg = all_diffs_neg && diff < 0
		prev = level
	}

	return all_diffs_neg || all_diffs_pos
}

func is_safe_with_dampener(levels []int) bool {
	if is_safe(levels) {
		return true
	}

	for i := range levels {
		damped_levels := make([]int, 0, len(levels)-1)
		for j, val := range levels {
			if i == j {
				continue
			}

			damped_levels = append(damped_levels, val)
		}

		if is_safe(damped_levels) {
			return true
		}
	}

	return false
}

func main() {
	f, err := os.Open("./two.txt")
	defer f.Close()
	check(err)

	n_safe := 0
	n_dampener_safe := 0

	scanner := bufio.NewScanner(f)
	for scanner.Scan() {

		line := scanner.Text()
		fields := strings.Fields(line)

		levels := make([]int, 0, 5)

		for _, field := range fields {
			level, err := strconv.Atoi(field)
			check(err)
			levels = append(levels, level)
		}
		if is_safe(levels) {
			n_safe += 1
		}
		if is_safe_with_dampener(levels) {
			n_dampener_safe += 1
		}
	}

	fmt.Println(n_safe)
	fmt.Println(n_dampener_safe)
}