find most common element

Programs to Find Most Common Element in an Unsorted Array

Given an unsorted array as an input, the goal is to find most common element or most frequent element or most repeating element in the array. Let’s solve this problem using the following methods i.e., Method 1: Sorting and Linear Traversal and Method 2: Using Hashing.


Algorithm: Method 1- Sorting and Linear Traversal

Example 1:


Time Complexity – O(nlogn) – Since the algorithm used in Arrays.sort() offer O(nlogn) performance.

Space Complexity – O(1)

Algorithm: Method 2- Use Hashing

Using Hashing to find the most common element is the efficient solution. Below is the algorithm for the same.

Example 2:


Time Complexity – O(n)

Space Complexity – O(n)

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