169. Majority Element

1. Description

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.
You may assume that the array is non-empty and the majority element always exist in the array.

2. Example

Example 1:
Input: [3,2,3]
Output: 3

Example 2:
Input: [2,2,1,1,1,2,2]
Output: 2

3. Solutions

Voting

n = i_nums.size()
Time complexity: O(n)
Space complexity: O(1)

class Solution {
public:
    int majorityElement(const vector<int>& nums) {
        int majority = 0, count = 0;
        for(int num : nums) {
            if(count == 0) {
                majority = num;
                count = 1;
            } else {
                count += num == majority ? 1 : -1;
            }
        }

        return majority;
    }
};