aoc2024/day-02/internal/two/check.go

package two

import (
	"math"
	"slices"
)

func withComparator(nums []int, comparator comparator, count int) bool {
	if count > 1 {
		return false
	}

	for i := 1; i < len(nums); i++ {
		if comparator(nums, i) || !isSafe(nums[i-1], nums[i]) {
			count++
			removeFirst, removeSecond := nextLevels(nums, i)
			return withComparator(removeFirst, comparator, count) ||
				withComparator(removeSecond, comparator, count)
		}
	}

	return true
}

func isSafe(m, n int) bool {
	return int(math.Abs(float64(m-n))) <= 3
}

func nextLevels(nums []int, i int) ([]int, []int) {
	first, second := slices.Clone(nums), slices.Clone(nums)
	return append(first[:i-1], first[i:]...), append(second[:i], second[i+1:]...)
}