Memoization solution for the house robber problem

Author: BarthJr

house_robber.py

@@ -0,0 +1,46 @@
+# You are a professional robber planning to rob houses along a street.
+# Each house has a certain amount of money stashed,
+# the only constraint stopping you from robbing each of them is that adjacent houses have security system connected
+# and it will automatically contact the police if two adjacent houses were broken into on the same night.
+
+# Given a list of non-negative integers representing the amount of money of each house,
+# determine the maximum amount of money you can rob tonight without alerting the police.
+
+from typing import List
+from unittest import TestCase
+
+
+def rob(nums: List[int]) -> int:
+    memo = [None] * (len(nums) + 1)
+    return _rob(0, nums, memo)
+
+
+def _rob(i, nums, memo):
+    if i > len(nums) - 1:
+        return 0
+    else:
+        if memo[i] is not None:
+            return memo[i]
+        result = max(nums[i] + _rob(i + 2, nums, memo), _rob(i + 1, nums, memo))
+        memo[i] = result
+        return result
+
+
+class TestRob(TestCase):
+    def test_with_empty_list(self):
+        self.assertEqual(0, rob([]))
+
+    def test_with_list_zeros(self):
+        self.assertEqual(0, rob([0, 0, 0, 0]))
+
+    def test_with_one_element(self):
+        self.assertEqual(2, rob([2]))
+
+    def test_with_two_elements_and_last_bigger(self):
+        self.assertEqual(2, rob([1, 2]))
+
+    def test_with_two_elements_and_first_bigger(self):
+        self.assertEqual(2, rob([2, 1]))
+
+    def test_if_not_return_max_profit_with_adjacent_houses(self):
+        self.assertEqual(4, rob([1, 2, 3, 1]))