House Robber II

Source

• leetcode: House Robber II

Note: This is an extension of House Robber.

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.

Java

public class Solution {

    private int robAlongALine(int[] nums){
        int a =0;
        int b=0;

        for(int i=0; i<nums.length; i++){
            if(i%2==0){
                a+=nums[i];
                a = Math.max(a, b);
            }
            else{
                b+=nums[i];
                b = Math.max(a, b);
            }
        }
        return Math.max(a, b);
    }

    public int rob(int[] nums) {
        if (nums.length == 0) return 0;
        if (nums.length == 1) return nums[0];
        if (nums.length == 2) return Math.max(nums[0], nums[1]);

        int maxWithFirst = robAlongALine(Arrays.copyOfRange(nums, 0, nums.length - 1));
        int maxWithoutFirst = robAlongALine(Arrays.copyOfRange(nums, 1, nums.length));
        return Math.max(maxWithFirst, maxWithoutFirst);
    }
}