229. Majority Element II

Given an integer array of size n, find all elements that appear more than ⌊ n/3 ⌋ times.

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

Example 1:

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

Example 2:

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

class Solution {
public:
    int val(vector<int> nums, int tar)
    {
        int ans = 0;
        for(auto item:nums)
        {
            if(item==tar)
                ans++;
        }
        return ans;
    }
    vector<int> majorityElement(vector<int>& nums) 
    {
        if(nums.size()<2)
            return nums;
        int k = 3;
        vector<int> ans;
        unordered_map<int, int> table;
        for(int i = 0;i<nums.size();i++)
        {   
            if(table.find(nums[i])!=table.end())
                table[nums[i]]++;
            else
            {
                if(table.size()<k-1)
                    table[nums[i]]++;
                else
                {
                    auto it=table.begin();
                    while(it!=table.end())
                    {                       
                        it->second--;
                        if(it->second==0)
                            it = table.erase(it);
                        else
                            it++;                        
                    }
                }
            }
        }
        for(auto it = table.begin();it!=table.end();it++)
            if(val(nums, it->first) > (nums.size()/k))
                ans.push_back(it->first);
        return ans;
    }
};