leetcode 213: House Robber II

Do the DP two times, one time starts from house 0 to house n-2 and one time starts from house 1 to house n-1. Return the maximum result.

class Solution {
public:
    int rob(vector<int>& nums) {
        if(nums.empty())
            return 0;
        int n=nums.size();
        if(n==1)
            return nums[0];
        int max1,max2;
        vector<int> dp(n,0);
        dp[0]=dp[1]=nums[0];
        for(int i=2;i<n-1;i++)
            dp[i]=max(dp[i-1],dp[i-2]+nums[i]);
        max1=dp[n-2];
        dp[1]=nums[1];
        dp[2]=max(nums[1],nums[2]);
        for(int i=3;i<n;i++)
            dp[i]=max(dp[i-1],dp[i-2]+nums[i]);
        max2=dp[n-1];
        return max(max1,max2);
    }
};