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  1. #include <bits/stdc++.h>
  2. using ll=long long int;
  3. using namespace std;
  4.  
  5. int main()
  6. {
  7.  
  8.    vector<int>a={1,1,1,1,2,2,2};
  9.    int n=a.size();
  10.    unordered_map<int,int>mp;
  11.    for(int i=0;i<n;i++){
  12.        mp[a[i]]++;
  13.    }
  14.    int ans=0;
  15.     for(auto i:mp){
  16.         if(i.second%3==0){
  17.             ans=ans+i.second/3;
  18.         }
  19.         else if(i.second%2==0){
  20.             ans=ans+i.second/2;
  21.         }     
  22.         else{
  23.             cout<<-1<<endl;
  24.             return 0;
  25.         }
  26.     }
  27.     cout<<ans<<endl;
  28.  
  29. }
Success #stdin #stdout 0.01s 5320KB
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https://ideone.com/QXnfjC
language:
C++ (gcc 8.3)
created:
1 day ago
visibility:
public

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