因为形成了环，遍历每个点为起始点，并排除相邻点，假设起始点必选。借用House Robber的解法即可。

class Solution {
public:
    int robOne(vector& nums) {
        if (nums.size()         {
            return 0;
        }
        vector v(nums.size() + 1);
        v[0] = 0;
        v[1] = nums[0];
        for (int i = 1;i < nums.size();i++)      {           int j = i + 1;          if (nums[i] + v[j - 2] > v[j - 1])
            {
                v[j] = nums[i] + v[j-2];
            }
            else
            {
                v[j] = v[j-1];
            }
        }
        return v[nums.size()];
    }
    int rob(vector& nums) {
        vector numsc;
        int size = nums.size();
        int sum = 0;
        for (int i = 0;i < size; i++)
        {
            numsc.clear();
            int tmp = nums[i];
            for (int j = i; j < size; j++)
            {
                if (j == ((i-1) < 0 ? i - 1 + size : i - 1) || j == ((i+1) >= size ? i + 1 - size : i + 1) || j == i)
                {
                    numsc.push_back(0);
                    continue;
                }
                numsc.push_back(nums[j]);
            }
            for (int j = 0; j < i; j++)
            {
                if (j == ((i-1) < 0 ? i - 1 + size : i - 1) || j == ((i+1) >= size ? i + 1 - size : i + 1) || j == i)
                {
                    numsc.push_back(0);
                    continue;
                }
                numsc.push_back(nums[j]);
            }
            tmp += robOne(numsc);
            if (tmp >= sum)
            {
                sum = tmp;
            }
        }
        return sum;
    }
};