如何在 C++ 中生成向量的不同排列？

Question

Suppose that there is a vector with only binary elements like this:

X = [0, 0, 1, 1]

The only distinct permutations are:

X = [0, 0, 1, 1]
X = [0, 1, 0, 1]
X = [0, 1, 1, 0]
X = [1, 0, 0, 1]
X = [1, 0, 1, 0]
X = [1, 1, 0, 0]

Is there an efficient way to do this in C++?

Answer 1

Use std::next_permutation :

#include <algorithm>
#include <array>
#include <cstdio>

int
main()
{
  std::array<int, 4> arr{ 0, 0, 1, 1 };

  /* Sort the array if necessary */
  std::sort(arr.begin(), arr.end());

  do {
    for (auto const e : arr)
      std::printf("%d ", e);
    std::putchar('\n');
  } while (std::next_permutation(arr.begin(), arr.end()));
}

Output:

0 0 1 1 
0 1 0 1 
0 1 1 0 
1 0 0 1 
1 0 1 0 
1 1 0 0 

Demo