C++ permutation

Sure! If you want to generate all permutations of a string or a set of elements in C++, you can use the `next_permutation` function from the `<algorithm>` library. Here's an example:

#include <iostream>
#include <algorithm>

int main() {
    std::string str = "abcd";

    // Sort the string in ascending order
    std::sort(str.begin(), str.end());

    // Generate and print all permutations
    do {
        std::cout << str << std::endl;
    } while (std::next_permutation(str.begin(), str.end()));

    return 0;
}

This code will print all possible permutations of the string "abcd". The `next_permutation` function generates the next lexicographically greater permutation of the string. When there are no more permutations, it returns `false`, and the loop ends.

You can modify this code to work with other types of containers or elements by replacing `std::string` with the appropriate container type.