leetcode213

 1 public class LEET_213 {
 2     public int rob(int[] nums) {
 3         if (nums == null || nums.length == 0) {
 4             return 0;
 5         }
 6         int n = nums.length;
 7         if (n == 1) {
 8             return nums[0];
 9         }
10         return Math.max(rob(nums, 0, n - 2), rob(nums, 1, n - 1));
11     }
12 
13     private int rob(int[] nums, int first, int last) {
14         int pre2 = 0, pre1 = 0;
15         for (int i = first; i <= last; i++) {
16             int cur = Math.max(pre1, pre2 + nums[i]);
17             pre2 = pre1;
18             pre1 = cur;
19         }
20         return pre1;
21     }
22 }

对比leetcode198：

 1 public class LEET_198 {
 2     public int rob(int[] nums) {
 3         int pre2 = 0, pre1 = 0;
 4         for (int i = 0; i < nums.length; i++) {
 5             int cur = Math.max(pre2 + nums[i], pre1);
 6             pre2 = pre1;
 7             pre1 = cur;
 8         }
 9         return pre1;
10     }
11 }