2966. Divide Array Into Arrays With Max Difference
Description
You are given an integer array nums
of size n
where n
is a multiple of 3 and a positive integer k
.
Divide the array nums
into n / 3
arrays of size 3 satisfying the following condition:
- The difference between any two elements in one array is less than or equal to
k
.
Return a 2D array containing the arrays. If it is impossible to satisfy the conditions, return an empty array. And if there are multiple answers, return any of them.
Example 1:
Input: nums = [1,3,4,8,7,9,3,5,1], k = 2
Output: [[1,1,3],[3,4,5],[7,8,9]]
Explanation:
The difference between any two elements in each array is less than or equal to 2.
Example 2:
Input: nums = [2,4,2,2,5,2], k = 2
Output: []
Explanation:
Different ways to divide nums
into 2 arrays of size 3 are:
- [[2,2,2],[2,4,5]] (and its permutations)
- [[2,2,4],[2,2,5]] (and its permutations)
Because there are four 2s there will be an array with the elements 2 and 5 no matter how we divide it. since 5 - 2 = 3 > k
, the condition is not satisfied and so there is no valid division.
Example 3:
Input: nums = [4,2,9,8,2,12,7,12,10,5,8,5,5,7,9,2,5,11], k = 14
Output: [[2,2,12],[4,8,5],[5,9,7],[7,8,5],[5,9,10],[11,12,2]]
Explanation:
The difference between any two elements in each array is less than or equal to 14.
Constraints:
n == nums.length
1 <= n <= 105
n
is a multiple of 31 <= nums[i] <= 105
1 <= k <= 105
Solutions
Solution 1: Sorting
First, we sort the array. Then, we take out three elements each time. If the difference between the maximum and minimum values of these three elements is greater than $k$, then the condition cannot be satisfied, and we return an empty array. Otherwise, we add the array composed of these three elements to the answer array.
The time complexity is $O(n \times \log n)$, and the space complexity is $O(n)$. Here, $n$ is the length of the array.
1 2 3 4 5 6 7 8 9 10 11 |
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
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1 2 3 4 5 6 7 8 9 10 11 12 |
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1 2 3 4 5 6 7 8 9 10 11 12 |
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