如何删除 C++ 中的重复排列

Question

#include <iostream>
using namespace std;

void RecPermute(string soFar, string rest)
{
    
    if (rest == "") {

        cout << soFar << endl;
    }
    else {


        for (int i = 0; i < rest.length(); i++) {
            string next = soFar + rest[i];
           
            string remaining = rest.substr(0, i) + rest.substr(i + 1);
            RecPermute(next, remaining);
            

        }
    }

}
void ListPermutations(string s) {
    RecPermute("",s);
}
int main()
{
    RecPermute("", "aab");
    return 0;

}

I am doing a college task, the task is to use this code to print characters permutations. this code is doing this but repeated characters result in repeated words. for example, if I entered "aab" the output will be: aab aba aab aba baa baa

Answer 1

This is the example source code from cppreference's std::next_permutation entry . It does exactly what you want and automatically does not include duplicates:

#include <algorithm>
#include <string>
#include <iostream>
 
int main()
{
    std::string s = "aba";
    std::sort(s.begin(), s.end());
    do {
        std::cout << s << '\n';
    } while(std::next_permutation(s.begin(), s.end()));
}

Output:

aab
aba
baa