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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3.  
  4. #define ll long long
  5.  
  6. void solve(){
  7.     int n;
  8.     cin>>n;
  9.     vector<int>a(n),b(n);
  10.     unordered_map<int,int>mp;
  11.     for(int &i:a)cin>>i;
  12.     for(int &i:b)cin>>i;
  13.  
  14.     priority_queue<pair<int,int>>p;
  15.     for(int i=0;i<n;i++){
  16.         if(a[i]==b[i])mp[a[i]]++;
  17.     }
  18.     for(auto &i:mp)p.push({i.second,i.first});
  19.     int ans=0;
  20.     while(p.size()>=2){
  21.         int top=p.top().first;
  22.         int elem=p.top().second;
  23.         p.pop();
  24.         int top2=p.top().first;
  25.         p.pop();
  26.         ans+=top2;
  27.         if(top-top2!=0)p.push({top-top2,elem});
  28.     }
  29.     if(p.size()==1){
  30.         int elem=p.top().second;
  31.         int top=p.top().first;
  32.         for(int i=0;i<n;i++){
  33.             if(top==0){
  34.                 cout<<ans<<"\n";
  35.                 return;
  36.             }
  37.             if(a[i]!=b[i]&&elem!=b[i]&&elem!=a[i]){
  38.                 top--;
  39.                 ans++;
  40.             }
  41.         }
  42.         if(top==0)cout<<ans<<"\n";
  43.         else cout<<-1;
  44.         return;
  45.     }
  46.     cout<<ans<<"\n";
  47.     // 1 1 2 3 2
  48.     // 1 1 1 1 3
  49. }
  50.  
  51. int main(){
  52.     ios_base::sync_with_stdio(false);
  53.     cin.tie(NULL);
  54.     solve();
  55.     return 0;
  56. }
Success #stdin #stdout 0.01s 5320KB
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stdin
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5
2 1 1 2 2
2 1 1 1 2
stdout
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2
https://ideone.com/dsvbYN
language:
C++14 (gcc 8.3)
created:
6 days ago
visibility:
public

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