198. House Robber （DP）

 1 class Solution {
 2     public int rob(int[] nums) {
 3         int n = nums.length;
 4         int[] res = new int[n + 1];
 5         if(n == 0) return 0;
 6         if(n == 1) return nums[0];
 7         if(n == 2) return Math.max(nums[1], nums[0]);
 8         res[0] = nums[0];
 9         res[1] = nums[1];
10         for(int i = 2; i < n; i++) {
11             for(int j = 0; j < i - 1; j++) {
12                 res[i] = Math.max(res[i], nums[i] + res[j]);
13             }
14         }
15         int max = 0;
16         for(int i = 0; i < n; i++) {
17             max = Math.max(max, res[i]);
18         }
19         return max;
20     }
21 }
22 
23 
24 //New
25 class Solution {
26     public int rob(int[] nums) {
27         int n = nums.length;
28         int[] res = new int[n];
29         if(n == 0) return 0;
30         if(n == 1) return nums[0];
31         if(n == 2) return Math.max(nums[1], nums[0]);
32         res[0] = nums[0];
33         res[1] = Math.max(nums[0], nums[1]);
34         for(int i = 2; i < n; i++) {
35             res[i] = Math.max(res[i - 1], nums[i] + res[i - 2]);    
36         }
37         return res[n - 1];
38     }
39 }