2025-06-18 Daily Challenge

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In: DailyChallenge

Today I have done leetcode's June LeetCoding Challenge with cpp.

June LeetCoding Challenge 18

Description

Divide Array Into Arrays With Max Difference

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 3
  • 1 <= nums[i] <= 105
  • 1 <= k <= 105

Solution

class Solution {
public:
  vector<vector<int>> divideArray(vector<int>& nums, int k) {
    sort(nums.begin(), nums.end());
    vector<vector<int>> answer;
    for(int i = 0; i < nums.size(); i += 3) {
      if(nums[i + 2] - nums[i] > k) return {};
      answer.push_back({nums[i], nums[i + 1], nums[i + 2]});
    }
    return answer;
  }
};

// Accepted
// 1117/1117 cases passed (46 ms)
// Your runtime beats 70.57 % of cpp submissions
// Your memory usage beats 64.59 % of cpp submissions (120.1 MB)
Algorithm