运用递归求n个元素的全排列

该问题答案如下：

#include<iostream>using namespace std;void f(string s,int k){if(k == s.length()){cout<<s<<endl;}for(int i = k; i < s.length(); i++){char a = s[k]; s[k] = s[i]; s[i] = a;//试探f(s,k+1);char b = s[k]; s[k] = s[i]; s[i] = b;//回溯}}int main(){string s = "abc";f(s,0);}