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  1. #include <bits/stdc++.h>
  2. typedef long long ll;
  3. using namespace std;
  4.  
  5. ll tc, a, b, c, ar[53];
  6.  
  7. ll fun (ll n){
  8. 	ll tmp = 0;
  9. 	for(int k = 1; k<= n/2 ; k++){
  10. 		if(k*2 == n){
  11. 			tmp += ar[k]/2;
  12. 		}
  13. 		else if(ar[k] > 0 && ar[n - k] > 0){
  14. 			tmp += min(ar[k], ar[n - k]);
  15. 		}
  16. 	}
  17. 	return tmp;
  18. }
  19.  
  20. int main() {
  21. 	scanf("%lld", &tc);
  22. 	while(tc--){
  23. 		scanf("%lld", &a);
  24. 		memset(ar, 0, sizeof(ar));
  25. 		ll maks = 1;
  26. 		for(int k = 1; k<= a; k++){
  27. 			scanf("%lld", &b);
  28. 			ar[b]++;
  29. 		}
  30. 		if(a == 1){
  31. 			printf("0\n");
  32. 			continue;
  33. 		}
  34. 		for(ll k = 2; k<= 2*a; k++){
  35. 			ll tmp = fun(k);
  36. 			maks = max(maks, tmp);
  37. 		}
  38. 		printf("%lld\n", maks);
  39. 	}
  40. }
Success #stdin #stdout 0s 4264KB
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https://ideone.com/dUU83a
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
public

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