diff --git a/counting-bits/aa601.py b/counting-bits/aa601.py
new file mode 100644
index 000000000..a81bc938d
--- /dev/null
+++ b/counting-bits/aa601.py
@@ -0,0 +1,10 @@
+'''
+TC: O(n)
+SC: O(n)
+'''
+class Solution:
+    def countBits(self, n: int) -> List[int]:
+        dp = [0] * (n + 1)
+        for num in range(1, n + 1):
+            dp[num] = dp[num // 2] + num % 2
+        return dp
diff --git a/house-robber-ii/aa601.py b/house-robber-ii/aa601.py
new file mode 100644
index 000000000..3e9ed945e
--- /dev/null
+++ b/house-robber-ii/aa601.py
@@ -0,0 +1,15 @@
+'''
+TC : O(n)
+SC : O(1)
+'''
+class Solution:
+    def rob(self, nums: List[int]) -> int:
+        if len(nums) == 1:
+            return nums[0]
+
+        def dp(start, end):
+            prv, cur = 0, 0
+            for idx in range(start, end):
+                prv, cur = cur, max(prv + nums[idx], cur)
+            return cur
+        return max(dp(1, len(nums)), dp(0, len(nums) - 1))