169. Majority Element

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.

Example 1:

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

Example 2:

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

 

Approach #1: HashMap. [C++]

class Solution {
public:
    int majorityElement(vector<int>& nums) {
        map<int, int> mp;
        int n = nums.size();
        int ans = 0;
        for (int num: nums) 
            mp[num]++;
        map<int, int>::iterator it;
        it = mp.begin();
        while (it != mp.end()) {
            if (it->second > n/2)
                ans = it->first;
            it++;
        }
        return ans;
    }
};