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  1. #include <stdio.h>
  2. #include <algorithm>
  3.  
  4. namespace algo
  5. {
  6.     template <typename it_t, typename d_it_t>
  7.     constexpr auto copy(it_t first, it_t last, d_it_t dfirst)
  8.     {
  9.         while(first != last)
  10.         {
  11.             *dfirst++ = *first++;
  12.         }
  13.     }
  14.  
  15.     template <typename it_t, typename value_t>
  16.     constexpr auto fill(it_t first, it_t last, const value_t& value)
  17.     {
  18.         while(first != last)
  19.         {
  20.             *first++ = value;
  21.         }
  22.     }
  23. }
  24.  
  25. template <typename ty, size_t n>
  26. class array
  27. {
  28. public:
  29.     constexpr auto begin()
  30.     {
  31.         return m_arr;
  32.     }
  33.  
  34.     constexpr auto end()
  35.     {
  36.         return m_arr + n;
  37.     }
  38.  
  39.     constexpr auto begin() const
  40.     {
  41.         return m_arr;
  42.     }
  43.  
  44.     constexpr auto end() const
  45.     {
  46.         return m_arr + n;
  47.     }
  48.  
  49.     constexpr auto& operator[](size_t i)
  50.     {
  51.         return m_arr[i];
  52.     }
  53.  
  54.     constexpr const auto& operator[](size_t i) const
  55.     {
  56.         return m_arr[i];
  57.     }
  58.  
  59.     constexpr auto& operator=(const array& rhs)
  60.     {
  61.         algo::copy(rhs.begin(), rhs.end(), begin());
  62.         return *this;
  63.     }
  64.  
  65. private:
  66.     ty m_arr[n]{};
  67. };
  68.  
  69.  
  70. template <size_t a, size_t b>
  71. class trapeze
  72. {
  73. public:
  74.     constexpr trapeze()
  75.     {
  76.         algo::fill(m_data.begin(), m_data.end(), ' ');
  77.         m_data[a*b] = '\0';
  78.     }
  79.  
  80.     constexpr auto& operator()(size_t i, size_t j)
  81.     {
  82.         return m_data[i*b + j];
  83.     }
  84.  
  85.     constexpr auto data() const
  86.     {
  87.         return m_data.begin();
  88.     }
  89.  
  90. private:
  91.     array<char, a * b + 1u> m_data; //+1 for '\0'
  92. };
  93.  
  94.  
  95. template <size_t max_a, size_t max_b>
  96. using trapeze_t = trapeze<std::max(max_a, max_b), std::max(max_a, max_b) + 1u>; //+1 for '\n'
  97.  
  98. template <size_t max_a, size_t max_b>
  99. constexpr auto generate_trapeze(size_t a, size_t b)
  100. {
  101.     trapeze_t<max_a, max_b> trapeze;
  102.  
  103.     if(a <= b)
  104.     {
  105.         for(size_t i = a; i <= b; i++) {
  106.             for(size_t j = 0; j < i ;j++) {
  107.                 trapeze(i - a, j) = '*';
  108.             }
  109.             trapeze(i - a, max_b) = '\n';
  110.         }
  111.     }
  112.     else
  113.     {
  114.         for(size_t i = a; static_cast<int>(i) >= static_cast<int>(b); --i) {
  115.             for(size_t j = 0; j < i; j++) {
  116.                 trapeze(a - i, j) = '*';
  117.             }
  118.             trapeze(a - i, max_b) = '\n';
  119.         }
  120.     }
  121.  
  122.     return trapeze;
  123. }
  124.  
  125. template <size_t a, size_t b>
  126. constexpr auto generate()
  127. {
  128.     constexpr auto max_a = a + 1u;
  129.     constexpr auto max_b = b + 1u;
  130.     using generated_trapezes_row_t = array<trapeze_t<max_a, max_b>, max_b>;
  131.     using generated_trapezes_t = array<generated_trapezes_row_t, max_a>;
  132.  
  133.     generated_trapezes_t generated_trapezes;
  134.  
  135.     for(size_t i = 0u; i < max_a; ++i)
  136.     {
  137.         for(size_t j = 0u; j < max_b; ++j)
  138.         {
  139.             generated_trapezes[i][j] = generate_trapeze<max_a, max_b>(i, j);
  140.         }
  141.     }
  142.  
  143.     return generated_trapezes;
  144. }
  145.  
  146. int main()
  147. {
  148.     constexpr auto max_a{ 10u };
  149.     constexpr auto max_b{ 10u };
  150.     constexpr auto trapezes = generate<max_a, max_b>();
  151.  
  152.     size_t a, b;
  153.  
  154.     scanf("%lu %lu", &a, &b);    
  155.  
  156.     printf("%s", trapezes[a][b].data());
  157. }
  158.  
Success #stdin #stdout 0s 16080KB
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stdout
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********** 
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https://ideone.com/OHED7g
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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