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  1. #include <iostream>
  2. #include <string>
  3.  
  4. using namespace std;
  5.  
  6. long long C(int n, int k) {
  7.     if (k > n / 2) k = n - k;
  8.     long long res = 1;
  9.     for (int i = 1; i <= k; ++i) res = res * (n - i + 1) / i;
  10.     return res;
  11. }
  12.  
  13. int main() {
  14.     ios_base::sync_with_stdio(0); 
  15.     cin.tie(0);
  16.  
  17.     string line;
  18.     while (getline(cin, line)) {
  19.         string s;
  20.         for (char c : line) {
  21.             if (c != ' ' && c != '\t' && c != '\r') s += c;
  22.         }
  23.         if (s.empty()) continue;
  24.  
  25.         int p = s.find('+'), r = s.find(')'), c = s.find('^');
  26.         if (p == -1 || r == -1 || c == -1) continue;
  27.  
  28.         string v1 = s.substr(1, p - 1);
  29.         string v2 = s.substr(p + 1, r - p - 1);
  30.         int n = stoi(s.substr(c + 1));
  31.  
  32.         if (!n) { 
  33.             cout << "1\n"; 
  34.             continue; 
  35.         }
  36.  
  37.         for (int k = 0; k <= n; ++k) {
  38.             long long v = C(n, k);
  39.             if (v > 1) cout << v;
  40.  
  41.             if (n - k) { 
  42.                 cout << v1; 
  43.                 if (n - k > 1) cout << "^" << n - k; 
  44.             }
  45.             if (k) { 
  46.                 cout << v2; 
  47.                 if (k > 1) cout << "^" << k; 
  48.             }
  49.  
  50.             if (k < n) cout << "+";
  51.         }
  52.         cout << "\n";
  53.     }
  54.     return 0;
  55. }
Success #stdin #stdout 0s 5320KB
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https://ideone.com/NLHoCS
(a+b+c)^2
language:
C++14 (gcc 8.3)
created:
6 hours ago
visibility:
public

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