#include <iostream>
#include <algorithm>
 
void permutation(std::string prefix, std::string remaining) {
    if (remaining.size() == 0) {
        std::cout << prefix << std::endl;
    } else {
        for (size_t i = 0; i < remaining.size(); ++i) {
            std::string nextPrefix = prefix + remaining[i];
            std::string nextRemaining = remaining;
            nextRemaining.erase(i, 1);
            permutation(nextPrefix, nextRemaining);
        }
    }
}
 
int main() {
    std::string numbers = "1234";
    permutation("", numbers);
    return 0;
}

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