2248. Intersection of Multiple Arrays

class Solution {
public:
    vector<int> intersection(vector<vector<int>>& nums) {
        vector<int> ans;
        unordered_map<int, int> m;
        int i = 0;
        for(int j = 0; j<nums[0].size(); j++)
        {
            m[nums[i][j]]++;
        }
        
        for(i=1; i<nums.size(); i++)
        {            
            for(int j=0; j<nums[i].size(); j++)
            {
                if(m.find(nums[i][j]) != m.end())
                {
                    m[nums[i][j]]++;
                }

            }
        }

        for(auto it = m.begin(); it != m.end(); it++)
        {
            if((it->second) == nums.size())
                ans.push_back(it->first);
        }

        sort(ans.begin(), ans.end());

        return ans;
    }
};