fork download
copy 
  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define ll long long
  4. #define dd double
  5. #define ld long double
  6. #define pi 3.14159265359
  7. #define ull unsigned long long
  8. #define yes cout<<"YES\n"
  9. #define no cout<<"NO\n"
  10. #define el "\n"
  11. #define Arwa ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  12. #define fix(x) cout<<fixed<<setprecision(x)
  13. ll gcd(ll a,ll b) {return b==0?a:gcd(b,a%b);}
  14. ll lcm(int a,int b) {return a/gcd(a,b)*b;}
  15. bool prime(ll n)
  16. {
  17. 	if(n==2) return true;
  18. 	if(n%2==0||n==1) return false;
  19. 	else { for(ll i=3; i*i<=n; i+=2) {if(n%i==0) return false;}}return true;
  20. }
  21. //here we go again
  22. int main()
  23. {
  24.     Arwa
  25.     int t=1;
  26.     //cin>>t;
  27.     while(t--)
  28.     {
  29.       int n,k,count=0;
  30.       ll freq[100]={};
  31.       cin>>n>>k;
  32.       int arr[n];
  33.       for(int i=0;i<n;i++)
  34.       cin>>arr[i];
  35.       for(int i=0;i<n;i++)
  36.       arr[i]%=k;
  37.       for(int i=0;i<n;i++)
  38.       freq[arr[i]]++;
  39.       if(freq[0])
  40.       {
  41.           count+=freq[0]/2*2;
  42.           freq[0]=0;
  43.       }
  44.       for(int i=1;i<k;i++)
  45.       {
  46.       if(freq[i]&&freq[k-i]&&i!=0)
  47.       {
  48.       freq[i]--;
  49.       freq[k-i]--;
  50.       count+=2;
  51.       }
  52.       }
  53.       cout<<count<<el;
  54.     }
  55.     return 0;
  56. }
  57. /*
  58. */
  59.  
  60.  
  61.  
  62.  
  63.  
  64.  
  65.  
  66.  
Success #stdin #stdout 0.01s 5288KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
0
https://ideone.com/LQPnS3
language:
C++ (gcc 8.3)
created:
4 days ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!