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.
Example
nums = [3,6,4], return 6
这题的做法是run两遍House Robber的算法 一遍包含第一个house不包含最后一个 二遍包含最后一个房子不包含第一个房子
实际上cover了三种case：1 含第一个不含最后一个 2 含最后一个不含第一个 3 两个全不包含
1 public class Solution {
2 /**
3 * @param nums: An array of non-negative integers.
4 * return: The maximum amount of money you can rob tonight
5 */
6 public int houseRobber2(int[] nums) {
7 // write your code here
8 if(nums==null||nums.length==0){
9 return 0;
10 }
11 if(nums.length==1) return nums[0];
12
13 return Math.max(helper(nums, 0, nums.length-2), helper(nums, 1, nums.length-1));
14 }
15 private int helper(int[] nums, int start, int end){
16 int f1 = 0;
17 int f2 = 0;
18
19 for(int i=start; i<=end; i++){
20 int temp1 = f1;
21 f1=Math.max(f1, f2+nums[i]);
22 f2=temp1;
23 }
24 return f1;
25 }
26 }
原文：http://www.cnblogs.com/xinqiwm2010/p/6835437.html