形式汇总：
7. Reverse Integer :120-21
189. Rotate Array:with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4].
[1,2,3,4,5,6,7]
[5,6,7,1,2,3,4]
REVERSE!REVERSE!REVERSE!
原文：http://www.cnblogs.com/immiao0319/p/7909816.html
