LeetCode 213 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.

思路

考虑不同时偷取第一个房子和最后一个房子。即：偷取范围[0 ~ n-2]和[1 ~ n-1].

代码如下：

class Solution {

    private int selectrob(int[] nums, int start) {
        int[] dp = new int[nums.length];
        dp[0] = 0;
        dp[1] = nums[start];
        for (int i = 2; i <= nums.length - 1; i++) {
            dp[i] = Math.max(dp[i - 2] + nums[i + start - 1], dp[i - 1]);
        }
        return dp[dp.length-1];
    }

    public int rob(int[] nums){
        int n = nums.length;
        if (nums == null || n == 0) {
            return 0;
        }
        if(n == 1){
            return nums[0];
        }
        return Math.max(selectrob(nums, 0), selectrob(nums, 1));
    }
}