House Robber II leetcode

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.

第一次去掉第一家保留最后一家 第二次去掉最后一家保留第一家, 计算能抢得最大值, 然后拿结果比较取最大的.

public class Solution {
    public int rob(int[] nums) {
        if (nums == null || nums.length == 0) {
            return 0;
        } else if (nums.length == 1) {
            return nums[0];
        } else if (nums.length == 2) {
            return Math.max(nums[0], nums[1]);
        }
        //include the first one
        int[] dp = new int[nums.length];
        dp[0] = 0;
        dp[1] = nums[0];
        for (int i = 2; i < nums.length; i++) {
            dp[i] = Math.max(dp[i - 1], dp[i - 2] + nums[i - 1]);
        }
        //include the last one
        int [] dr = new int[nums.length];
        dr[0] = 0;
        dr[1] = nums[1];
        for (int i = 2; i < nums.length; i++) {
            dr[i] = Math.max(dr[i - 1], dr[i - 2] + nums[i]);
        }
        return Math.max(dp[nums.length - 1], dr[nums.length - 1]);
    }
}