House Robber II

Description:

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 non-negative integers representing the amount of money of each house, determine the maximum amount of money you can rob tonight without alerting the police.

Solution:

class Solution {
public:
	int rob(vector<int>& nums) {
		auto sz = (int)nums.size();
		if (sz == 0) return 0;
		int pre1 = 0, cur1 = nums[0], pre2 = 0, cur2 = nums[sz-1];
		for (int i = 1; i < sz-1; ++i) {
			int tmp1 = cur1, tmp2 = cur2;
			cur1 = max(cur1, pre1+nums[i]);
			cur2 = max(cur2, pre2+nums[sz-i-1]);
			pre1 = tmp1;
			pre2 = tmp2;
		}
		return max(cur1, cur2);
	}
};