字符串的全排列

#include <iostream>
using namespace std;

void permutation(char* str,char *start)
{
    if(*start=='\0')
         cout<<str<<endl;
    else
    {
        for(char* pchar = start;*pchar!='\0';++pchar)
        {
            char temp = *start;
            *start = *pchar;
            *pchar = temp;
            permutation(str,start+1);   
            temp = *start;
            *start = *pchar;
            *pchar = temp;          
        }

    }
}
int main()
{
    char* str;
    while(cin>>str)
    {
        permutation(str,str);

    }
    return 0;
}

另外一种结果返回方式

class Solution {
    unordered_set<string> res;
    vector<string>save;
public:

void perm(string& str, char *pbegin, char *pstr, unordered_set<string>& res)
{
    if (*pstr == '\0')
    {
        res.insert(str);
    }
    else
    {
        // res.push_back(str);
        for (char* ptr = pstr; *ptr != '\0'; ++ptr)
        {
            swap(*ptr, *pstr);
            perm(str, pbegin, pstr + 1, res);
            swap(*ptr, *pstr);
        }
    }
}
vector<string> Permutation(string str) {

    if (str.length() == 0)
        return save;
    //res.push_back(str);
    perm(str, &str[0], &str[0], res);
    //res.pop_back();
    for (unordered_set<string>::iterator it = res.begin(); it!=res.end(); ++it)
    {
        save.push_back(*it);
    }
    sort(save.begin(),save.end());
    return save;
}

};