leetcode-213 House Robber II

Twice pass:

1. rob nums[0](抢第一个，不抢最后一个房子）
2. not rob nums[0]（不抢第一个，抢最后一个）
   
   

<span style="font-family:Microsoft YaHei;font-size:14px;">class Solution {public:    int rob(vector<int>& nums) {        int len = nums.size();        if(len == 0) return 0;        if(len == 1) return nums[0];                int res1 = 0, prev1 = 0;                       for(int i = 0; i < len -1; i++){            int tmp = prev1;            prev1 = res1;            res1 = max(tmp+nums[i],prev1);        }                int res2 = 0,prev2 = 0;        for(int j = 1; j < len; j++){            int tmp = prev2;            prev2 = res2;            res2 = max(tmp+nums[j],prev2);        }        return max(res1,res2);    }};</span>