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  1. #include <iostream>
  2. #include <set>
  3.  
  4. using namespace std;
  5.  
  6. int countSpecialElements(int a[], int n) {
  7.     set<int> s;
  8.     int cnt = 0;
  9.  
  10.     for (int i = 0; i < n; ++i) {
  11.         for (int j = 0; j < i; ++j) {
  12.             if (s.count(a[i] - a[j]) || s.count(a[i] + a[j])) {
  13.                 ++cnt;
  14.                 break;
  15.             }
  16.         }
  17.         for (int j = 0; j <= i; ++j) {
  18.             s.insert(a[i] + a[j]);
  19.         }
  20.     }
  21.  
  22.     return cnt;
  23. }
  24.  
  25. int main() {
  26.  
  27.     int n;
  28.     cin >> n;
  29.     int a[n];
  30.     for (int i = 0; i < n; ++i) cin >> a[i];
  31.  
  32.     cout << countSpecialElements(a, n);
  33.  
  34.     return 0;
  35. }
  36.  
Success #stdin #stdout 0.01s 5276KB
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https://ideone.com/YJQX98
language:
C++14 (gcc 8.3)
created:
17 days ago
visibility:
public

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