[leetcode][c]25. Reverse Nodes in k-Group

大致想法是這樣:
[framePrev]->[frame: k nodes]->[frameNext]

然後allocate stack(k 個pointer), 用來存放一個k個node 的指標
將此frame 反轉後，再將frame 往後移

source code:
https://github.com/cy-arduino/leetcode/blob/master/25.%20Reverse%20Nodes%20in%20k-Group.py
https://github.com/cy-arduino/leetcode/blob/master/25.%20Reverse%20Nodes%20in%20k-Group.c