TheLuckyString | Topcoder Archive

Problem Statement

John and Brus are studying string theory at the university. According to Brus, a string is called lucky if no two consecutive characters are equal. John is analyzing a String s, and he wants to know how many distinct lucky strings can be generated by reordering the letters in s. If s is a lucky string in its original ordering, it should also be considered in the count.

Definition

Class:: TheLuckyString
Method:: count
Parameters:: String
Returns:: int
Method signature:: int count(String s)
(be sure your method is public)

Constraints

s will contain between 1 and 10 characters, inclusive.
Each character of s will be a lowercase letter ('a' - 'z').

Examples

```
"ab"
```
```
Returns: 2
```
Two lucky strings - "ab" and "ba".
```
"aaab"
```
```
Returns: 0
```
It's impossible to construct a lucky string.
```
"aabbbaa"
```
```
Returns: 1
```
"abababa" is the only lucky string that can be generated.
```
"abcdefghij"
```
```
Returns: 3628800
```

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