产生全排列:
#include <iostream>
#include <algorithm>
using namespace std;
int main() {
string s = "0123456789";
int n;
cin >> n;
int cnt = 1;
do {
if(cnt == n) {
cout << s;
break;
}
cnt++;
}while(next_permutation(s.begin(), s.end()));
return 0;
}