[yuseok89] WEEK 14 Solutions

binary-tree-level-order-traversal/yuseok89.py

@@ -0,0 +1,29 @@
+# TC: O(N)
+# SC: O(N)
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def levelOrder(self, root: TreeNode | None) -> list[list[int]]:
+
+        ret = []
+
+        def preOrder(root: TreeNode | None, height: int):
+            if len(ret) == height:
+                ret.append([])
+
+            ret[height].append(root.val)
+
+            if root.left:
+                preOrder(root.left, height + 1)
+            if root.right:
+                preOrder(root.right, height + 1)
+
+        if root:
+            preOrder(root, 0)
+
+        return ret
+

counting-bits/yuseok89.py

@@ -0,0 +1,17 @@
+# TC: O(N)
+# SC: O(N)
+class Solution:
+    def countBits(self, n: int) -> list[int]:
+        ans = []
+
+        upper = 1
+        ans.append(0)
+
+        for idx in range(1, n + 1):
+            ans.append(ans[idx - upper] + 1)
+
+            if idx == upper:
+                upper *= 2
+
+        return ans
+

house-robber-ii/yuseok89.py

@@ -0,0 +1,19 @@
+# TC: O(N)
+# SC: O(1)
+class Solution:
+    def rob(self, nums: list[int]) -> int:
+
+        n = len(nums)
+
+        def calc(nums, s, e):
+            rob, skip = 0, 0
+            for idx in range(s, e):
+                rob, skip = skip + nums[idx], max(rob, skip)
+
+            return max(rob, skip)
+
+        if n == 1:
+            return nums[0]
+
+        return max(calc(nums, 0, n - 1), calc(nums, 1, n))
+