输出一个字符串的全排列

#include<iostream>

#include<cstring>

using namespace std;



void swap(char &a, char &b)

{

    char t = a;

    a = b;

    b = t;

}

void permutation(char ch[],int s, int e)

{

    int i = 0;

    if(s > e)

        return;

    if(s == e)

    {

        for(i=0; i<=e; i++)

            cout<<ch[i];

        cout<<endl;

        return;

    }

    for(i=s; i<=e; i++)

    {

        bool isExist = false;

        for(int j=i-1; j>=s; j--)

            if(ch[j] == ch[i])

            {

                isExist = true;

                break;

            }

        if(!isExist)

        {

            swap(ch[s],ch[i]);

            permutation(ch,s+1,e);

            swap(ch[s],ch[i]);

        }

    }

}

int main()

{

    char ch[100];

    cout<<"please input the string!"<<endl;

    cin>>ch;

    int len = strlen(ch);

    permutation(ch,0,len-1);

    cout<<""<<endl;

    return 0;

}