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169. Majority Element

Difficulty Topics

Description

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

 

Follow-up: Could you solve the problem in linear time and in O(1) space?

Solution

majority-element.py
class Solution:
    def majorityElement(self, nums: List[int]) -> int:
        n = len(nums)
        majority = nums[0]
        count = 1

        for i in range(1, n):
            if nums[i] != majority:
                count -= 1
            else:
                count += 1

            if count == 0:
                majority = nums[i]
                count = 1

        return majority