Generating permutation has always been an important problem in computer science. In this problem
you will have to generate the permutation of a given string in ascending order. Remember that your
algorithm must be efficient.
Input
The first line of the input contains an integer n, which indicates how many strings to follow. The next
n lines contain n strings. Strings will only contain alpha numerals and never contain any space. The
maximum length of the string is 10.
Output
For each input string print all the permutations possible in ascending order. Not that the strings should
be treated, as case sensitive strings and no permutation should be repeated. A blank line should follow
each output set.
Sample Input
3
ab
abc
bca
Sample Output
ab
ba
abc
acb
bac
bca
cab
cba
abc
acb
bac
bca
cab
cba

題目應該是很簡單了，就是幾個字母的組合，要是重複的就只打出一個來就行了
全排列可以用深搜實現，也可以用c++函式，在這裡我用的函式，程式碼短。
程式碼如下：

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

char s[11];

int main()
{
	int t;
	scanf("%d",&t);
	getchar(); 
	while(t--)
	{
		gets(s);
		int len=strlen(s);
		sort(s,s+len);//首先一開始的順序應該是有序的。
		do{    
			puts(s);
  		} while ( next_permutation(s,s+len) );//字典序有小到大。
  		printf("\n");
	}
}
 

努力加油a啊，(^o)/~