Add Solution2.java for 0198.House Robber (doocs#225)

Merged doocs#225

Author: huaxu1024

solution/0198.House Robber/Solution2.java

@@ -0,0 +1,9 @@
+class Solution {
+    public int rob(int[] nums) {
+        int[] dp = new int[nums.length + 2];
+        for (int i = 0; i < nums.length; i++) {
+            dp[i + 2] = Math.max(dp[i] + nums[i], dp[i + 1]);
+        }
+        return dp[nums.length + 1];
+    }
+}