2966. Divide Array Into Arrays With Max Difference - Explanation

class Solution:
    def divideArray(self, nums: List[int], k: int) -> List[List[int]]:
        nums.sort()
        res = []

        for i in range(0, len(nums), 3):
            if nums[i + 2] - nums[i] > k:
                return []
            res.append(nums[i: i + 3])

        return res

class Solution:
    def divideArray(self, nums: List[int], k: int) -> List[List[int]]:
        max_num = max(nums)
        count = [0] * (max_num + 1)
        for num in nums:
            count[num] += 1

        res = []
        group = []

        for num in range(max_num + 1):
            while count[num] > 0:
                group.append(num)
                count[num] -= 1

                if len(group) == 3:
                    if group[2] - group[0] > k:
                        return []
                    res.append(group)
                    group = []

        return res