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  1. #include <vector>
  2. #include <string>
  3. #include <iostream>
  4. #include <iomanip>
  5.  
  6. using namespace std;
  7.  
  8. class Gray
  9. {
  10. public:
  11.     Gray(int N):N(N),a(N+1,false),last_(-1){}
  12.     ~Gray() = default;
  13.     Gray(const Gray&) = default;
  14.     Gray(Gray&&)      = default;
  15.     Gray& operator=(const Gray&) = default;
  16.     Gray& operator=(Gray&&)      = default;
  17.  
  18.     size_t size() const { return N; }
  19.     void reset(size_t newN = 0)
  20.     {
  21.         if (newN) N = newN;
  22.         vector<bool> b(N+1,false);
  23.         std::swap(a,b);
  24.         last_ = -1;
  25.     }
  26.  
  27.     bool operator[](size_t idx) const { return a[idx]; }
  28.  
  29.     int  last() const { return last_; }
  30.  
  31.     bool next()
  32.     {
  33.         size_t j;
  34.         if (!a[N]) j = 0; else {
  35.             for(j = 0; j < N; ++j) if (a[j]) break;
  36.             ++j;
  37.         }
  38.         if (j == N) return false;
  39.         a[N] = !a[N];
  40.         a[j] = !a[j];
  41.         last_ = j;
  42.         return true;
  43.     }
  44. private:
  45.     vector<bool> a;
  46.     size_t N;
  47.     int last_;
  48. };
  49.  
  50.  
  51.  
  52. int main(int argc, const char * argv[])
  53. {
  54.     int m[] = { 2, 3, 5, 7 };
  55.  
  56.     Gray g(sizeof(m)/sizeof(m[0]));
  57.     do {
  58.         if (g.last() >= 0)
  59.         {
  60.             int p = 1;
  61.             for(size_t i = 0; i < g.size(); ++i) if (g[i]) p *= m[i];
  62.             cout << setw(6) << p << " = ";
  63.             for(size_t i = 0, first = 1; i < g.size(); ++i)
  64.                 if (g[i]) {
  65.                     if (!first)
  66.                     {
  67.                         cout << " * ";
  68.                     }
  69.                     else
  70.                     {
  71.                         first = 0;
  72.                     }
  73.                     cout << m[i];
  74.                 }
  75.             cout << "\n";
  76.         }
  77.     } while(g.next());
  78.  
  79.     // Только произведения - если нет нулевого элемента.
  80.  
  81.     g.reset();
  82.  
  83.     int p = 1;
  84.     do {
  85.         if (g.last() >= 0)
  86.         {
  87.             if (g[g.last()]) p *= m[g.last()]; else p /= m[g.last()];
  88.             cout << setw(6) << p <<"\n";
  89.         }
  90.     } while(g.next());
  91.  
  92. }
  93.  
Success #stdin #stdout 0s 3468KB
comments (?)
stdin 
Standard input is empty
stdout 
     2 = 2
     6 = 2 * 3
     3 = 3
    15 = 3 * 5
    30 = 2 * 3 * 5
    10 = 2 * 5
     5 = 5
    35 = 5 * 7
    70 = 2 * 5 * 7
   210 = 2 * 3 * 5 * 7
   105 = 3 * 5 * 7
    21 = 3 * 7
    42 = 2 * 3 * 7
    14 = 2 * 7
     7 = 7
     2
     6
     3
    15
    30
    10
     5
    35
    70
   210
   105
    21
    42
    14
     7
https://ideone.com/EDj72o
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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