213. House Robber II

class Solution(object):
    def rob(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        #index 0: does not steal from the first house
        #index 1: steal from the first house 
        if not nums:return 0
        res=[0,0]
        #if steal from the first house, then can not steal from the last house
        res[0]=nums[0]+self.helper(nums[1:-1])[1]
        #if does not steal from the first house
        res[1]=max(self.helper(nums[1:]))
        return max(res)
    def helper(self,nums):
        if not nums:return [0,0]
        curr=self.helper(nums[1:])
        return [nums[0]+curr[1],max(curr)]