Is Limit Occurrences in Sorted Array easy or hard?

Limit Occurrences in Sorted Array is generally considered an Easy problem. The challenge is recognizing that sorted order allows duplicate checks using simple index comparisons. Once the two-pointer pattern is applied, the implementation becomes straightforward.

Limit Occurrences in Sorted Array Python/Java solution

Python and Java implementations both follow the same pattern: maintain a write pointer and iterate through the array with a read pointer. When the element does not violate the allowed occurrence limit, assign it to the write index and increment the pointer. This produces an in-place O(n) solution with constant extra memory.

How to solve Limit Occurrences in Sorted Array in O(n)?

Use a two-pointer approach. Maintain a write index and iterate through the array with a read pointer. For each element, check whether placing it would exceed the allowed number of duplicates by comparing it with the element k positions behind the write index. If valid, copy it and move the write pointer forward.

What is the best approach for Limit Occurrences in Sorted Array?

The best approach uses a two-pointer technique. A slow pointer tracks where the next valid element should be written while a fast pointer scans the array. Because the array is sorted, comparing the current value with the element k positions before the write pointer ensures no value appears more than k times. This solution runs in O(n) time with O(1) extra space.

Is Limit Occurrences in Sorted Array asked at Google/Amazon/Meta?

Duplicate removal and frequency-limiting problems on sorted arrays frequently appear in interviews at companies like Google, Amazon, and Meta. Variants such as "Remove Duplicates from Sorted Array" and "Remove Duplicates from Sorted Array II" test the same two-pointer pattern and in-place array manipulation.

What data structure is used in Limit Occurrences in Sorted Array?

The problem mainly uses arrays with the two-pointer technique. Since the input array is already sorted, duplicates can be detected using index comparisons instead of hash maps or extra storage.

What is the time complexity of Limit Occurrences in Sorted Array?

The optimal algorithm runs in O(n) time because the array is scanned once using two pointers. Each element is read once and written at most once. Space complexity is O(1) since the modification happens directly inside the input array.

3940. Limit Occurrences in Sorted Array - Practice Online

You are given a sorted integer array nums and an integer k.

Return an array such that each distinct element appears at most k times, while preserving the relative order of the elements in nums.

Example 1:

Input: nums = [1,1,1,2,2,3], k = 2

Output: [1,1,2,2,3]

Explanation:

Each element can appear at most 2 times.

The element 1 appears 3 times, so only 2 occurrences are kept.
The element 2 appears 2 times, so both occurrences are kept.
The element 3 appears 1 time, so it is kept.

Thus, the resulting array is [1, 1, 2, 2, 3].

Example 2:

Input: nums = [1,2,3], k = 1

Output: [1,2,3]

Explanation:

All elements are distinct and already appear at most once, so the array remains unchanged.

Constraints:

1 <= nums.length <= 100
1 <= nums[i] <= 100
nums is sorted in non-decreasing order.
1 <= k <= nums.length

Follow-up:

Can you solve this in-place using O(1) extra space?
Note that the space used for returning or resizing the result does not count toward the space complexity mentioned above, as some languages do not support in-place resizing.