diff --git a/house-robber/kayden.py b/house-robber/kayden.py
new file mode 100644
index 000000000..97f71ee52
--- /dev/null
+++ b/house-robber/kayden.py
@@ -0,0 +1,11 @@
+class Solution:
+    # 시간복잡도: O(N)
+    # 공간복잡도: O(1)
+    def rob(self, nums: List[int]) -> int:
+        one, two = 0, 0
+
+        for num in nums:
+            temp = max(two+num, one)
+            two, one = one, temp
+
+        return one
diff --git a/lowest-common-ancestor-of-a-binary-search-tree/kayden.py b/lowest-common-ancestor-of-a-binary-search-tree/kayden.py
new file mode 100644
index 000000000..fc4d30ca8
--- /dev/null
+++ b/lowest-common-ancestor-of-a-binary-search-tree/kayden.py
@@ -0,0 +1,20 @@
+class Solution:
+    # 시간복잡도: O(N)
+    # 공간복잡도: O(1)
+    def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
+        def find(node):
+            if not node:
+                return None
+
+            left = find(node.left)
+            right = find(node.right)
+
+            if node == p or node == q:
+                return node
+
+            if left and right:
+                return node
+
+            return left or right
+
+        return find(root)
diff --git a/meeting-rooms/kayden.py b/meeting-rooms/kayden.py
new file mode 100644
index 000000000..e2445952f
--- /dev/null
+++ b/meeting-rooms/kayden.py
@@ -0,0 +1,14 @@
+class Solution:
+    # 시간복잡도: O(NlogN)
+    # 공간복잡도: O(1)
+    def can_attend_meetings(self, intervals: List[Interval]) -> bool:
+        intervals.sort()
+
+        prev = 0
+        for start, end in intervals:
+            if end < prev:
+                return False
+
+            prev = end
+
+        return True