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  1. #include <array>
  2. #include <cstdlib>
  3.  
  4. namespace sehn {
  5.     template <typename T, std::size_t N>
  6.     using matrix = std::array<std::array<T, N>, N>;
  7.  
  8.     template <typename T, std::size_t N>
  9.     matrix<T, N> flipud (matrix<T, N> const &);
  10.  
  11.     template <typename T, std::size_t N, int K>
  12.     std::array<T, N - std::abs (K)> diag (matrix<T, N> const &);
  13. }
  14.  
  15. #include <iostream>
  16.  
  17. template <typename T, std::size_t N>
  18. std::array<int, 2 * N - 1> sum_diags (sehn::matrix<T, N> const &);
  19.  
  20. int main () {
  21.     std::size_t const size (3);
  22.     sehn::matrix<int, size> m { {
  23.            1,   2,   3,
  24.           10,  20,  30,
  25.          100, 200, 300
  26.     } };
  27.  
  28.     for (auto const &row : m) {
  29.         for (auto const &item : row)
  30.             std::cout << item << '\t';
  31.         std::cout << std::endl;
  32.     }
  33.     std::cout << std::endl;
  34.  
  35.     for (auto const &s : sum_diags (m))
  36.         std::cout << s << '\t';
  37.     std::cout << std::endl << std::endl;
  38.  
  39.     auto f (sehn::flipud (m));
  40.  
  41.     for (auto const &row : f) {
  42.         for (auto const &item : row)
  43.             std::cout << item << '\t';
  44.         std::cout << std::endl;
  45.     }
  46.     std::cout << std::endl;
  47.  
  48.     for (auto const &s : sum_diags (f))
  49.         std::cout << s << '\t';
  50.     std::cout << std::endl << std::endl;
  51.  
  52.     return 0;
  53. }
  54.  
  55. #include <iterator>
  56. #include <numeric>
  57. #include <type_traits>
  58.  
  59. template <typename T, std::size_t N, int K>
  60. typename std::enable_if<K < static_cast<int> (N) - 1>::type
  61.     sum_diags_impl (sehn::matrix<T, N> const &, std::array<int, 2 * N - 1> &);
  62.  
  63. template <typename T, std::size_t N, int K>
  64. typename std::enable_if<K == static_cast<int> (N) - 1>::type
  65.     sum_diags_impl (sehn::matrix<T, N> const &, std::array<int, 2 * N - 1> &);
  66.  
  67. template <typename T, std::size_t N>
  68. std::array<int, 2 * N - 1> sum_diags (sehn::matrix<T, N> const &source) {
  69.     std::array<int, 2 * N - 1> sums;
  70.     sum_diags_impl<T, N, -N + 1> (source, sums);
  71.     return sums;
  72. }
  73.  
  74. template <typename T, std::size_t N, int K>
  75. typename std::enable_if<K < static_cast<int> (N) - 1>::type
  76.     sum_diags_impl (sehn::matrix<T, N> const &matrix, std::array<int, 2 * N - 1> &sums) {
  77.         auto diag = sehn::diag<T, N, K> (matrix);
  78.         sums[N - 1 + K] = std::accumulate (std::begin (diag), std::end (diag), T{});
  79.         sum_diags_impl<T, N, K + 1> (matrix, sums);
  80. }
  81.  
  82. template <typename T, std::size_t N, int K>
  83. typename std::enable_if<K == static_cast<int> (N) - 1>::type
  84.     sum_diags_impl (sehn::matrix<T, N> const &matrix, std::array<int, 2 * N - 1> &sums) {
  85.         auto diag = sehn::diag<T, N, K> (matrix);
  86.         sums[N - 1 + K] = std::accumulate (std::begin (diag), std::end (diag), T{});
  87. }
  88.  
  89. #include <utility>
  90.  
  91. namespace sehn {
  92.     template <typename T, std::size_t N>
  93.     matrix<T, N> flipud (matrix<T, N> const &source) {
  94.         matrix<T, N> clone (source);
  95.  
  96.         for (std::size_t i (0); i < N / 2; ++i)
  97.             std::swap (clone[i], clone[N - 1 - i]);
  98.  
  99.         return clone;
  100.     }
  101.  
  102.  
  103.     template <typename T, std::size_t N, int K>
  104.     std::array<T, N - std::abs (K)> diag (matrix<T, N> const &source) {
  105.         std::array<T, N - std::abs (K)> tmp;
  106.  
  107.         for (std::size_t i (0); i < N; ++i) {
  108.             std::size_t j (i + K);
  109.             if (j < N)
  110.                 tmp[std::min (i, j)] = source[i][j];
  111.         }
  112.  
  113.         return tmp;
  114.     }
  115. }
Success #stdin #stdout 0s 3296KB
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stdin
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Standard input is empty
stdout
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1	2	3	
10	20	30	
100	200	300	

100	210	321	32	3	

100	200	300	
10	20	30	
1	2	3	

1	12	123	230	300
https://ideone.com/gENiTQ
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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