其它
In how many ways can the letters in $CPCCKBY$ be rearranged so that $C$ cannot be put in both ends and two or more $C$s do not appear together? 
Overseas Competition->Knowledge Point->Counting Modules->Permutations and Combinations
There are $3$ $C$s in total now with other $4$ letters remaining.  There are $\_4P\_4$ ways for us to arrange the $4$ letters\textquotesingle{} positions.  So the answer is $\_4P\_4=24$. 