UVa 10338 - Mischievous Children

// UVa 10338 - Mischievous Children

#include <iostream>
#include <string>
#include <string.h>
using namespace std;

#define integer unsigned long long

int main() {
	integer f[21];
	f[0] = 1;
	for (int i = 1; i <= 20; i++)
		f[i] = f[i - 1] * i;
	int tt;
	cin >> tt;
	for (int t = 1; t <= tt; t++) {
		string word;
		cin >> word;
		int c[26];
		memset(c, 0, sizeof(c));
		for (int i = 0; i < word.length(); i++)
			c[word[i] - 'A']++;
		integer sol = f[word.length()];
		for (int ch = 0; ch < 26; ch++)
			sol /= f[c[ch]];
		cout << "Data set " << t << ": " << sol << endl;
	}
	return 0;
}