Is Divide Array in Sets of K Consecutive Numbers easy or hard?

The problem is generally classified as Medium difficulty on coding platforms. The logic is straightforward once you recognize the greedy pattern with frequency counting, but handling duplicates and ensuring correct sequence formation can be tricky without sorting and proper hash map management.

Divide Array in Sets of K Consecutive Numbers Python/Java solution

In both Python and Java, the typical implementation uses a map or dictionary to store frequencies and processes numbers in sorted order. For each smallest available value, attempt to build a group of k consecutive numbers by decrementing counts in the map. If any required value is missing, return false; otherwise continue until all elements are used.

How to solve Divide Array in Sets of K Consecutive Numbers in O(n)?

Pure O(n) time is difficult because ordering of numbers is required to build consecutive groups. Most correct solutions first sort the array, resulting in O(n log n) complexity. After sorting, a hash map or greedy extension technique ensures each element is processed efficiently while forming valid sequences.

What is the best approach for Divide Array in Sets of K Consecutive Numbers?

The most reliable approach sorts the array and uses a hash map to track frequencies. For each smallest unused number, try forming a sequence of length k by checking x, x+1, ..., x+k-1. Decrement counts as you build groups. This greedy counting technique runs in O(n log n) time due to sorting and O(n) space for the frequency map.

Is Divide Array in Sets of K Consecutive Numbers asked at Google/Amazon/Meta?

Variants of this problem appear in interviews at large tech companies including Amazon, Google, and Meta. The question tests understanding of hash maps, greedy grouping, and handling ordered sequences in arrays. Interviewers typically expect a frequency-map greedy solution with clear reasoning about consecutive ranges.

What data structure is used in Divide Array in Sets of K Consecutive Numbers?

The primary data structure is a hash table (frequency map) that stores how many times each number appears. Sorting the array ensures numbers are processed in increasing order. Some optimized solutions also maintain an additional map tracking sequences that end at a specific number.

What is the time complexity of Divide Array in Sets of K Consecutive Numbers?

The optimal solution runs in O(n log n) time because the array must be sorted before forming groups. After sorting, each element is processed a constant number of times using hash map lookups. Space complexity is O(n) for storing element frequencies and sequence tracking.

Description Hints 3 Solution Video 20:41

1296. Divide Array in Sets of K Consecutive Numbers

Medium59.2% acceptance2 companies

Given an array of integers nums and a positive integer k, check whether it is possible to divide this array into sets of k consecutive numbers.

Return true if it is possible. Otherwise, return false.

Example 1:

Input: nums = [1,2,3,3,4,4,5,6], k = 4
Output: true
Explanation: Array can be divided into [1,2,3,4] and [3,4,5,6].

Example 2:

Input: nums = [3,2,1,2,3,4,3,4,5,9,10,11], k = 3
Output: true
Explanation: Array can be divided into [1,2,3] , [2,3,4] , [3,4,5] and [9,10,11].

Example 3:

Input: nums = [1,2,3,4], k = 3
Output: false
Explanation: Each array should be divided in subarrays of size 3.

Constraints:

1 <= k <= nums.length <= 10⁵
1 <= nums[i] <= 10⁹

Note: This question is the same as 846: https://leetcode.com/problems/hand-of-straights/

Asked at 2 companies

Waymo

Google

Topics

Hints open one at a time

Hint 1

If the smallest number in the possible-to-split array is V, then numbers V+1, V+2, ... V+k-1 must contain there as well.

Hint 2

You can iteratively find k sets and remove them from array until it becomes empty.

Hint 3

Failure to do so would mean that array is unsplittable.

20:41

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