permutation求全排列

include <iostream>
#include <string>
 
using namespace std;
 
void swap(char &c1, char &c2){
    char tmp = c1;
    c1= c2;
    c2= tmp;
}
 
void perm(string s, int i, int n){
 
    if(i== n){
        cout << s << endl;
    }
 
    for(int j=i;j<=n;j++){
        swap(s[i], s[j]);
        perm(s, i+, n);
        swap(s[i], s[j]);
    }
 
}
 
int main(){
 
    string p= "";
    perm(p, , );
 
}