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;
  }
 }