Algorithm Puzzles: Majority Element

Algorithm Puzzles everyday every week sometimes: Majority Element

Puzzle

Puzzle from leetcode:

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.

Solution

class Solution {
public:
    int majorityElement(const vector<int>& nums) {
        std::unordered_map<int, int> map;
        int currentMajority = 0;

        for(auto iter = nums.begin(); iter != nums.end(); iter++) {
            map[*iter]++;
            if(map[*iter] > nums.size() / 2) {
                currentMajority = *iter;
                break;
            }
        }

        return currentMajority;
    }
};

T.C.: O(N)
S.C.: O(N)