Unique_Number_of_Occurrences.cpp

class Solution {
public:
    bool uniqueOccurrences(vector<int>& arr) {
        unordered_map<int, int> m;
        for(int i=0; i<arr.size(); i++){
            m[arr[i]]++;
        }
        unordered_set<int> s;
        for(auto x : m ){
            int freq = x.second;
            if(s.find(freq) != s.end()) return false;
            else{
                s.insert(freq);
            }
        }
        return true;
    }
};