1207. Unique Number of Occurrences

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problem

solution

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class Solution {
public:
    bool uniqueOccurrences(vector<int>& arr) {
        unordered_map<int, int> mp;
        unordered_set<int> s;
        for(int a:arr) mp[a]++;
        for(auto it = mp.begin() ; it!=mp.end() ; ++it)
        {
            if(s.count(it->second)) return false;
            s.insert(it->second);
        }
        return true;
        
    }
};

analysis

  • time complexity O(n)
  • space complexity O(n)