169

169. Majority Element (Easy)

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
• -231 <= nums[i] <= 231 - 1

 

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

Companies:
Microsoft, Apple, Facebook, Amazon, Google, Adobe, Rubrik

Related Topics:
Array, Hash Table, Divide and Conquer, Sorting, Counting

Similar Questions:

• Majority Element II (Medium)
• Check If a Number Is Majority Element in a Sorted Array (Easy)

Solution 1.

// OJ: https://leetcode.com/problems/majority-element/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    int majorityElement(vector<int>& nums) {
        int ans = 0, cnt = 0;
        for (int n : nums) {
            if (ans == n) ++cnt;
            else if (cnt > 0) --cnt;
            else {
                ans = n;
                cnt = 1;
            }
        }
        return ans;
    }
};