213. House Robber II

class Solution {
    public int rob(int[] nums) {
        if(nums.length==0)
            return 0;
        if(nums.length==1)
            return nums[0];
        return Math.max(rob1(nums, 0, nums.length-1), rob1(nums, 1, nums.length));
    }
    private int rob1(int[] nums, int i, int j){
        int[] dp=new int[j];
        for(int k=i;k<j;k++)
        {
            int num1=k>=2?dp[k-2]:0;
            int num2=k>=1?dp[k-1]:0;
            dp[k]=Math.max(num1+nums[k], num2);
        }
        return dp[j-1];
    }
}