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  1. #include <iostream>
  2. #include <vector>
  3. using namespace std;
  4. int main(){
  5.     ios_base::sync_with_stdio(0);
  6.     cin.tie(0);
  7.     cout.tie(0);
  8.     int n,k,sum=0;
  9.     cin>>n>>k;
  10.     vector<int> v(n+5);
  11.     int freq1[100005]={0},freq2[100005]={0};
  12.     for(int i=0;i<n;i++){
  13.         cin>>v[i];
  14.         if(v[i]<=100000){
  15.             freq1[v[i]]++;
  16.         }
  17.         if(v[i]>100000){
  18.             freq2[v[i]-100000]++;
  19.         }
  20.     }
  21.     for(int i=0;i<n;i++){
  22.         for(int j=i+1;j<n;j++){
  23.             if((v[i]+v[j])%k==0||(k%(v[i]+v[j])==0)){
  24.                  if(v[i]>100000&&v[j]>100000){
  25.                  if(v[i]==v[j]){
  26.                  if(freq2[v[i]-100000]>=2){
  27.                         sum+=2;
  28.                         freq2[v[i]-100000]--;
  29.                         freq2[v[j]-100000]--;
  30.                       //  cout<<v[i]<<" "<<v[j]<<" ";
  31.                         break;   
  32.                 }
  33.             }
  34.           else if(freq2[v[i]-100000]>0&&freq2[v[j]-100000]>0){
  35.                         sum+=2;
  36.                         freq2[v[i]-100000]--;
  37.                         freq2[v[j]-100000]--;
  38.                         // cout<<v[i]<<" "<<v[j]<<" ";
  39.                         break;
  40.                 }
  41.                 }
  42.              if(v[i]<=100000&&v[j]<=100000){
  43.                  if(v[i]==v[j]){
  44.                     if(freq1[v[i]]>=2){
  45.                         sum+=2;
  46.                         freq1[v[i]]--;
  47.                         freq1[v[j]]--;
  48.                       //  cout<<v[i]<<" "<<v[j]<<" ";
  49.                         break;
  50.                 }
  51.                 }
  52.                else if(freq1[v[i]]>0&&freq1[v[j]]>0){
  53.                         sum+=2;
  54.                         freq1[v[i]]--;
  55.                         freq1[v[j]]--;
  56.                         // cout<<v[i]<<" "<<v[j]<<" ";
  57.                         break;
  58.                 }
  59.             }
  60.             else if(v[i]>100000&&v[j]<=100000){
  61.                 if(freq2[v[i]-100000]>0&&freq1[v[j]]>0){
  62.                         sum+=2;
  63.                         freq2[v[i]-100000]--;
  64.                         freq1[v[j]]--;
  65.                       //   cout<<v[i]<<" "<<v[j]<<" ";
  66.                         break;
  67.                 }
  68.             }
  69.             else if(v[i]<=100000&&v[j]>100000){
  70.                 if(freq1[v[i]]>0&&freq2[v[j]-100000]>0){
  71.                         sum+=2;
  72.                         freq1[v[i]]--;
  73.                         freq2[v[j]-100000]--;
  74.                        // cout<<v[i]<<" "<<v[j]<<" ";
  75.                         break;
  76.                 }
  77.             }
  78.         }
  79.     }
  80.     }
  81.     cout<<sum;
  82. }
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/KMnwyS
language:
C++ (gcc 8.3)
created:
10 days ago
visibility:
public

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