week 5 198. House Robber.

public class Solution {
    public int rob(int[] nums) {
        if(nums == null || nums.length == 0){
            return 0;
        }
    if(nums.length == 1){
        return nums [0];
    }
    return helper (nums, nums.length - 1);
    }
    
    public int helper(int [] nums, int pos){
        if (pos == 0){
            return nums[0];
        }
        if(pos == 1){
            return Math.max(nums[0], nums[1]);
        }
        
        return Math.max(helper(nums, pos - 1), helper(nums, pos - 2) + nums[pos]);
    }
}