Update 198_House_Robber.java

Author: Sean Prashad

Dynamic Programming/198_House_Robber.java

@@ -4,23 +4,14 @@ public int rob(int[] nums) {
             return 0;
         }
 
-        int[] memo = new int[nums.length];
-        Arrays.fill(memo, -1);
-        return helper(nums, 0, memo);
-    }
+        int currHouse = 0, oneHouseAgo = 0, twoHousesAgo = 0;
 
-    private int helper(int[] nums, int idx, int[] memo) {
-        if (idx >= nums.length) {
-            return 0;
+        for (int i = 0; i < nums.length; i++) {
+            currHouse = Math.max(twoHousesAgo + nums[i], oneHouseAgo);
+            twoHousesAgo = oneHouseAgo;
+            oneHouseAgo = currHouse;
         }
 
-        if (memo[idx] != -1) {
-            return memo[idx];
-        }
-
-        int result = Math.max(helper(nums, idx + 1, memo), helper(nums, idx + 2, memo) + nums[idx]);
-
-        memo[idx] = result;
-        return result;
+        return currHouse;
     }
 }