169. Majority Element

Problem Link

Description

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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

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Python3

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