C++ :

#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<iostream>
using namespace std;
int n;
int b[150]={0};
char a[600];
long long sum=0;
int print()
{
	sum++;
	for(int i=1;i<=n;++i)
	{
		cout<<a[i];
	}
	printf("\n");
}
int search(int i)
{
	for(int j='a';j<='z';++j)
	{
		if(b[j]!=0)
		{
			a[i]=j;
			b[j]--;
			if(i==n)
			{
				print();
			}
			else
			{
				search(i+1);
			}
			b[j]++;
		}
	}
}

int main()
{
	cin>>n;
	char c;
	for(int i=1;i<=n;++i)
	{
		cin>>c;
		b[c]++; 
	}
	search(1);
	cout<<sum;
	return 0;
} 

Pascal :

var
 a:array['a'..'z'] of longint;
 b:array[0..501] of char;
 i,j,n,tot:longint;
 s:char;

procedure search(k:longint);
 var i:longint;
  j:char;
  begin
   if (k>n) then
    begin
     inc(tot);
     for i:=1 to n do write(b[i]);
     writeln;
     exit;
    end;
  for j:='a' to 'z' do
   if a[j]>0 then begin
    b[k]:=j;
    dec(a[j]);
    search(k+1);
    inc(a[j]);
   end;
 end;

begin
 readln(n);
 for i:=1 to n do
  begin
   read(s);
   inc(a[s]);
  end;
 search(1);
 writeln(tot);
end.

Java :

/*
public class Main5544 {  
  
    public static void main(String[] args) {  
        int[] a = { 1,1,2,2};  
        System.out.println(perm(a, 0));  
    }  
  
    public static int perm(int[] a, int begin) {  
        if (begin == a.length) {  
            for (int i = 0; i < a.length; i++) {  
                System.out.print(a[i] + " ");  
            }  
            System.out.println();  
            return 1;  
        }  
  
        int count = 0;  
        for (int i = begin; i < a.length; i++) {  
            if(isSwap(a,begin,i)){  
                swap(a, begin, i);  
                count += perm(a, begin + 1);  
                swap(a, begin, i);  
            }             
        }  
        return count;  
    }  
  
    public static void swap(int[] a, int begin, int end) {  
        int temp = a[begin];  
        a[begin] = a[end];  
        a[end] = temp;  
    }  
      
    public static boolean isSwap(int[] a,int begin,int end){          
        for(int i=end;i>begin;i--){  
            if(a[end]==a[i-1]){  
                return false;  
            }  
        }  
        return true;      
    }  
  
}  */
import java.util.Iterator;
import java.util.Scanner;
import java.util.TreeSet;


public class Main {
	static TreeSet<String> list;
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		while(in.hasNextInt()){
			int n = in.nextInt();
			String str = in.next();
			char[] s = str.toCharArray();
			list = new TreeSet<String>();
			int count = perm(s,0);
			Iterator<String> it = list.iterator();
			while(it.hasNext())
				System.out.println(it.next());
			System.out.println(count);
		}
	}
	public static int perm(char[] s, int i) {
		if (i == s.length) {
			String str = new String(s);
			list.add(str);
			return 1;
		}
		int count = 0;
		for (int j = i; j < s.length; j++) {
			if (isSwap(s, i, j)) {
				swap(s, j, i);
				count+=perm(s, i + 1);
				swap(s, j, i);
			}
		}
		return count;
	}

	public static void swap(char[] s, int i, int j) {
		char t = s[i];
		s[i] = s[j];
		s[j] = t;
	}

	public static boolean isSwap(char[] a, int begin, int end) {
		/*for (int i = end; i > begin; i--) {
			if (a[end] == a[i - 1]) {
				return false;
			}
		}*/
		for(int i=begin;i<end;i++)
			if(a[end]==a[i])
				return false;
		return true;
	}  
}