IMP:house robber II

 int rob(vector<int>& nums) {
        int n=nums.size();
        if(n<2)return n?nums[0]:0;
        return max(test(nums,0,n-2),test(nums,1,n-1));
    }
    int test(vector<int>v,int l,int r)
    {
        int i,cur=0,pre=0,tmp;
        for(i=l;i<=r;i++)
        {
            tmp=max(v[i]+pre,cur);
            pre=cur;
            cur=tmp;
        }
        return tmp;
    }