DSA Leetcode 150 Top Interview Question

5. Majority Element

Given an array nums of size n, return the majority element.

The majority element is the element that appears more than ⌊n / 2⌋ times. You may assume that the majority element always exists in the array.

Example 1:

Input: nums = [3,2,3]
Output: 3

Example 2:

Input: nums = [2,2,1,1,1,2,2]
Output: 2

Constraints:

• n == nums.length
• 1 <= n <= 5 * 104
• -109 <= nums[i] <= 109

Solution:

class Solution {
    func majorityElement(_ nums: [Int]) -> Int {
            var counts = [Int: Int]()
            let majority = nums.count / 2

            for num in nums {
                counts[num, default: 0] += 1
                if counts[num]! > majority {
                    return num
                }
            }

            return -1 
    }
}