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234. Majority Element – Part 1
Objective: Given an array of integer write an algorithm to find the majority element in it (if exist).
Majority Element: If an element appears more than n/2 times in array where n is the size of the array.
Example:
int [] arrA = {1,3,5,5,5,5,4,1,5};
Output: Element appearing more than n/2 times: 5
int []arrA = {1,2,3,4};
Output: No element appearing more than n/2 times
Click here to read O(n) approach-Boyer–Moore majority vote algorithm
Approach 1: Brute Force
Use nested for loops and count each element and if count>n/2 for each element.
Time Complexity: O(n^2)
Approach 2: Hash Map
- Store the count of each element in Hash map.
- Iterate through hash map and check if any element has count >n/2
Time Complexity: O(n), Space Complexity: O(n)
Approach 3: Sorting
- Sort array, this will bring all the same elements together.
- Iterate through array and check if any element has count >n/2
Time Complexity: O(nlogn), Space Complexity: O(1)
Output:
Element appearing more than n/2 times: 5