The government of a small but important country has decided that the alphabet needs to be streamlined and reordered. Uppercase letters will be eliminated. They will issue a royal decree in the form of a String of B and A characters. The first character in the decree specifies whether a must come ( B )Before b in the new alphabet or ( A )After b . The second character determines the relative placement of b and c , etc. So, for example, "BAA" means that a must come Before b , b must come After c , and c must come After d .
Any letters beyond these requirements are to be excluded, so if the decree specifies k comparisons then the new alphabet will contain the first k+1 lowercase letters of the current alphabet.
Create a class Alphabet that contains the method choices that takes the decree as input and returns the number of possible new alphabets that conform to the decree. If more than 1,000,000,000 are possible, return -1.
Definition
版本更新了一下，到5.84了，需要用VS.net平臺進行編譯運行，介紹與原來的一樣！
磁盤文件的安全刪除，我們通常所執行的刪除操作并不是真正的刪除只是清除了文件的fat表內容，文件數據還在磁盤上，可以恢復，所以不安全。-disk deletion of the security document, we usually enforced by the delete operation does not really delete the file will simply remove the fat table of contents, document data on the disk is, can be restored, therefore unsafe.
漢諾塔！！！
Simulate the movement of the Towers of Hanoi puzzle Bonus is possible for using animation
eg. if n = 2 A→B A→C B→C
if n = 3 A→C A→B C→B A→C B→A B→C A→C
