Is Count Elements With at Least K Greater Values easy or hard?

The problem is generally considered medium difficulty. The logic becomes straightforward once you recognize that the k-th largest element defines a threshold. The challenge lies in translating the "k greater elements" condition into a ranking or selection problem.

Count Elements With at Least K Greater Values Python/Java solution

In Python or Java, the typical solution sorts the array and identifies the k-th largest value using index n - k. Then iterate through the array and count elements strictly smaller than this threshold. The implementation is short and runs in O(n log n) time with constant or linear auxiliary space depending on the sorting implementation.

How to solve Count Elements With at Least K Greater Values in O(n)?

Use Quickselect to find the k-th largest element in the array without fully sorting it. This value becomes the threshold such that any element strictly smaller than it has at least k greater elements. After finding the threshold, perform one linear pass to count qualifying elements, giving O(n) average time complexity.

What is the best approach for Count Elements With at Least K Greater Values?

The most practical approach is sorting the array and identifying the k-th largest value as a threshold. After sorting, any element strictly smaller than nums[n - k] has at least k greater values. This solution runs in O(n log n) time and uses minimal extra space, making it easy to implement and reliable in interviews.

Is Count Elements With at Least K Greater Values asked at Google/Amazon/Meta?

Problems involving order statistics, k-th largest elements, and array ranking frequently appear in interviews at companies like Google, Amazon, and Meta. Variants often test sorting, heap usage, or Quickselect. This problem specifically checks whether you can translate a ranking condition into a threshold-based solution.

What data structure is used in Count Elements With at Least K Greater Values?

The core structure is a simple array. Algorithms commonly applied include sorting or selection algorithms like Quickselect. Some variations may also use heaps or binary search over sorted arrays to determine how many elements are greater than a given value.

What is the time complexity of Count Elements With at Least K Greater Values?

The common sorting solution runs in O(n log n) time due to the sorting step, followed by a linear scan. A brute force approach takes O(n²) time because each element compares against all others. Using Quickselect to find the k-th largest element reduces the average complexity to O(n).

3759. Count Elements With at Least K Greater Values - Practice Online

You are given an integer array nums of length n and an integer k.

An element in nums is said to be qualified if there exist at least k elements in the array that are strictly greater than it.

Return an integer denoting the total number of qualified elements in nums.

Example 1:

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

Output: 2

Explanation:

The elements 1 and 2 each have at least k = 1 element greater than themselves.
No element is greater than 3. Therefore, the answer is 2.

Example 2:

Input: nums = [5,5,5], k = 2

Output: 0

Explanation:

Since all elements are equal to 5, no element is greater than the other. Therefore, the answer is 0.

Constraints:

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