poj 1256 按一定顺序输出全排列（next_permutation）

Sample Input

3
aAb
abc
acba
Sample Output

Aab
Aba
aAb
abA
bAa
baA
abc
acb
bac
bca
cab
cba
aabc
aacb
abac
abca
acab
acba
baac
baca
bcaa
caab
caba
cbaa

对字符串进行全排列，字符的大小规则： 'A'<'a'<'B'<'b'<...<'Z'<'z'.

 # include <iostream>
 # include <cstring>
 # include <algorithm>
 using namespace std;  

 bool cmp(const char &a, const char &b)
    {
     if (tolower(a) == tolower(b))  //把字符转换成小写字母,非字母字符不做出处理
    {
        return a < b;
     }
     else
        return tolower(a) < tolower(b);

 }

 int main()
 {
     int num = ;
     cin >> num;
     while(num--)
     {
         char str[];
         cin >> str;
         int length = strlen(str);
         sort(str, str+length, cmp);
         cout << str << endl;
         while(next_permutation(str, str + length, cmp))  //全排列
         {
             cout << str << endl;
         }
     }
     return ;
 }