213. House Robber II
After robbing those houses on that street, the thief has found himself a new place for his thievery so that he will not get too much attention. This time, all houses at this place are arranged in a circle. That means the first house is the neighbor of the last one. Meanwhile, the security system for these houses remain the same as for those in the previous street.
Given a list of nonnegative integers representing the amount of money of each house, determine the maximum amount of money you can rob tonight without alerting the police.
这个问题是分两种情况考虑，把两种问题分别解决，再求最大值就可以了
 偷第一个，不偷最后一个
 不偷第一个


Ref: https://discuss.leetcode.com/topic/14375/simpleacsolutioninjavainonwithexplanation