随笔 - C++ 的高维向量

发表于 更新于 分类于 ， 本文字数： 39 阅读时长 ≈ 1 分钟

为了方便写高维数组以及初始化，就简单封了一个结构体

代码

ndvector.hppview raw
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#ifndef NDSEIVE_HPP
#define NDSEIVE_HPP 1

#include <algorithm>
#include <vector>

template <size_t N, class Tp>
struct ndvector: public std::vector<ndvector<N - 1, Tp>> {
  static_assert(N > 0, "N should be positive");

  using base_tp = ndvector<N - 1, Tp>;
  using base = std::vector<base_tp>;
  using self = ndvector<N, Tp>;

  template <class T, typename... Ts>
  ndvector(T &&n, Ts &&...args): base(n, base_tp(args...)) {}

  constexpr size_t dim() const { return N; }

  template <class T>
  void fill(T &&x) {
    for (auto &i : *this) i.fill(x);
  }
};

template <class Tp>
struct ndvector<1, Tp>: public std::vector<Tp> {
  using base = std::vector<Tp>;
  using self = ndvector<1, Tp>;

  template <class T>
  ndvector(T &&n): base(n) {}

  constexpr size_t dim() const { return 1; }

  template <class T>
  void fill(T &&x) {
    std::fill(this->begin(), this->end(), x);
  }
};

#endif

测试

ndvector_test.cppview raw
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#include <iostream>
#include "ndvector.hpp"

using std::cout, std::endl;

template <
  class Ch,
  class Tr,
  class Ct,
  std::enable_if_t<std::is_same<decltype(std::declval<Ct>().begin()),
                                typename Ct::iterator>::value &&
                   std::is_same<decltype(std::declval<Ct>().end()),
                                typename Ct::iterator>::value> * = nullptr>
std::basic_ostream<Ch, Tr> &operator<<(std::basic_ostream<Ch, Tr> &os,
                                       const Ct &x) {
  if (x.begin() == x.end()) return os << "[]";
  os << '[';
  for (auto it = x.begin(); it != x.end() - 1; ++it) os << *it << ", ";
  return os << x.back() << ']';
}

#define OUTPUT_(x) cout << #x << ": " << x << endl

int main() {
  ndvector<5, int> v(5, 4, 3, 2, 1);
  OUTPUT_(v.dim());
  OUTPUT_(v[0].dim());
  OUTPUT_(v[0][0].dim());
  OUTPUT_(v);
  v.fill(114514);
  OUTPUT_(v);

  cout << "==========" << endl;

  ndvector<5, int> v2(5, 4, 0, 2, 1);
  OUTPUT_(v2.dim());
  OUTPUT_(v2);
  return 0;
}

// clang-format off
/* outout:
v.dim(): 5
v[0].dim(): 4
v[0][0].dim(): 3
v: [[[[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]]], [[[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]]], [[[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]]], [[[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]]], [[[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]], [[[0], [0]], [[0], [0]], [[0], [0]]]]]
v: [[[[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]]], [[[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]]], [[[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]]], [[[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]]], [[[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]], [[[114514], [114514]], [[114514], [114514]], [[114514], [114514]]]]]
==========
v2.dim(): 5
v2: [[[], [], [], []], [[], [], [], []], [[], [], [], []], [[], [], [], []], [[], [], [], []]]
*/