Is Check if an Array Is Consecutive easy or hard?

Check if an Array Is Consecutive is generally categorized as an easy problem. The main challenge is recognizing the mathematical property that max - min + 1 must equal the array length and combining it with duplicate detection.

Check if an Array Is Consecutive Python/Java solution

In Python, a set is used to store numbers while checking duplicates and validating the range condition. Java solutions typically use HashSet for the same purpose. Both implementations achieve O(n) time complexity and O(n) extra space.

How to solve Check if an Array Is Consecutive in O(n)?

Compute the minimum and maximum values in the array and check if max - min + 1 equals n. Then insert every element into a hash set. If a duplicate appears or the range condition fails, return false; otherwise the array forms a consecutive sequence.

What is the best approach for Check if an Array Is Consecutive?

The most efficient approach uses a hash set along with minimum and maximum values. First compute min and max, then verify that max - min + 1 equals the array length. Insert elements into a set to detect duplicates. This guarantees O(n) time complexity and O(n) space.

Is Check if an Array Is Consecutive asked at Google/Amazon/Meta?

Problems involving consecutive sequences and hash set validation frequently appear in interviews at large tech companies such as Amazon, Google, and Meta. Variants often test understanding of range checks, duplicate detection, and hash-based lookups.

What data structure is used in Check if an Array Is Consecutive?

The optimal approach uses a hash set to store elements and check duplicates in constant time. This data structure allows fast membership checks while scanning the array once.

What is the time complexity of Check if an Array Is Consecutive?

The optimal solution runs in O(n) time using a hash table to track elements and detect duplicates. Sorting-based solutions take O(n log n), while brute force approaches can degrade to O(n²) due to repeated scans.

Description Hints 2 Solution Video 4:16

2229. Check if an Array Is Consecutive

Easy61.6% acceptancePremium elsewhere, free here

Given an integer array nums, return true if nums is consecutive, otherwise return false.

An array is consecutive if it contains every number in the range [x, x + n - 1] (inclusive), where x is the minimum number in the array and n is the length of the array.

Example 1:

Input: nums = [1,3,4,2]
Output: true
Explanation:
The minimum value is 1 and the length of nums is 4.
All of the values in the range [x, x + n - 1] = [1, 1 + 4 - 1] = [1, 4] = (1, 2, 3, 4) occur in nums.
Therefore, nums is consecutive.

Example 2:

Input: nums = [1,3]
Output: false
Explanation:
The minimum value is 1 and the length of nums is 2.
The value 2 in the range [x, x + n - 1] = [1, 1 + 2 - 1], = [1, 2] = (1, 2) does not occur in nums.
Therefore, nums is not consecutive.

Example 3:

Input: nums = [3,5,4]
Output: true
Explanation:
The minimum value is 3 and the length of nums is 3.
All of the values in the range [x, x + n - 1] = [3, 3 + 3 - 1] = [3, 5] = (3, 4, 5) occur in nums.
Therefore, nums is consecutive.

Constraints:

1 <= nums.length <= 10⁵
0 <= nums[i] <= 10⁵

Topics

Hints open one at a time

Hint 1

Try sorting nums.

Hint 2

If nums is consecutive and sorted in ascending order, then nums[i] + 1 = nums[i + 1] for every i in the range 0 ≤ i < nums.length - 1.

4:16

Still stuck?Read the written solution, or watch a walkthrough.

Open solution

2229. Check if an Array Is Consecutive

Topics

Hints open one at a time

Similar problems