Is Count Elements With Maximum Frequency easy or hard?

LeetCode classifies this problem as Easy. The main skill required is building and using a frequency map with a hash table, a common pattern in array and counting problems.

Count Elements With Maximum Frequency Python/Java solution

In Python, a dictionary or collections.Counter can track frequencies, while Java typically uses HashMap . Both implementations iterate through the array, update counts, track the maximum frequency, and sum occurrences of elements with that maximum.

How to solve Count Elements With Maximum Frequency in O(n)?

Traverse the array and store frequencies in a hash map. Track the maximum frequency while updating counts. After processing all elements, sum the frequencies of values whose count equals the maximum frequency. This approach requires O(n) time and O(n) space.

What is the best approach for Count Elements With Maximum Frequency?

The most efficient approach uses a hash table to count the frequency of each element in one pass through the array. After building the frequency map, track the maximum frequency and sum the counts of all elements that match it. This runs in O(n) time and O(n) space.

Is Count Elements With Maximum Frequency asked at Google/Amazon/Meta?

Frequency counting problems are common in interviews at companies like Amazon, Google, and Meta because they test hash table usage and array traversal. Variations of this problem appear frequently in coding rounds and online assessments.

What data structure is used in Count Elements With Maximum Frequency?

A hash table (or dictionary/map) is the primary data structure used. It stores the frequency of each integer in the array and allows constant-time updates and lookups, making it ideal for counting-based problems.

What is the time complexity of Count Elements With Maximum Frequency?

The optimal solution runs in O(n) time because each element in the array is processed once while updating a frequency map. A second pass over the map to sum the maximum frequencies also takes linear time relative to unique elements, keeping the overall complexity O(n).

Description Hints 2 Solution Video 12:50

3005. Count Elements With Maximum Frequency

Easy79.8% acceptance8 companies

You are given an array nums consisting of positive integers.

Return the total frequencies of elements in nums such that those elements all have the maximum frequency.

The frequency of an element is the number of occurrences of that element in the array.

Example 1:

Input: nums = [1,2,2,3,1,4]
Output: 4
Explanation: The elements 1 and 2 have a frequency of 2 which is the maximum frequency in the array.
So the number of elements in the array with maximum frequency is 4.

Example 2:

Input: nums = [1,2,3,4,5]
Output: 5
Explanation: All elements of the array have a frequency of 1 which is the maximum.
So the number of elements in the array with maximum frequency is 5.

Constraints: