Majority Element II

Given an integer array of size n, find all elements that appear more than

⌊ n/3 ⌋

times. The algorithm should run in linear time and in O(1) space.

Analyse: map.

Runtime: 40ms.

class Solution {
public:
vector<int> majorityElement(vector<int>& nums) {
int n = nums.size();
map<int, int> m;
vector<int> result;

for(int i = 0; i < n; i++){
if(m.find(nums[i]) != m.end())
m[nums[i]]++;
else
m[nums[i]] = 1;
}

for(map<int, int>::iterator ite = m.begin();  ite != m.end(); ite++){
if(ite->second > n / 3)
result.push_back(ite->first);
}
return result;
}
};