1 #include <iostream>
2 #include <map>
3 typedef unsigned long long ullong;
4 using std::string;
5
6 ullong factorial(ullong i) {
7 if (i > 1) {
8 return i * factorial(i - 1);
9 }
10 if (i == 1) {
11 return 1;
12 }
13 if (i == 0) {
14 return 0;
15 }
16 }
17
18 ullong count(const string &s) {
19 using std::map;
20 map<char, ullong> repeat_nums;
21 for (ullong i = 0; i < s.length(); i++) {
22 repeat_nums[s[i]]++;
23 }
24 ullong result = factorial(s.length());
25 for (auto it = repeat_nums.begin(); it != repeat_nums.end(); it++) {
26 if (it->second > 1) {
27 result /= factorial(it->second);
28 }
29 }
30 return result;
31 }
32
33 int main() {
34 std::cout << count("ABA") << std::endl;
35 std::cout << count("ABCDEFGHHA") << std::endl;
36 std::cout << count("AABBCC") << std::endl;
37 }
