[Lyla] Week 14

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

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+'''
+시간 복잡도: O(n)
+공간 복잡도: O(n)
+'''
+
+from collections import deque
+from typing import List, Optional
+
+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: Optional[TreeNode]) -> List[List[int]]:
+        queue = deque([root]) if root else []
+        result = []
+
+        while queue:
+            same_level_nodes = []
+
+            for _ in range(len(queue)):
+                node = queue.popleft()
+                same_level_nodes.append(node.val)
+
+                if node.left:
+                    queue.append(node.left)
+                if node.right:
+                    queue.append(node.right)
+
+            result.append(same_level_nodes)
+
+        return result

counting-bits/pmjuu.py

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+'''
+시간 복잡도: O(n)
+공간 복잡도: O(n)
+'''
+from typing import List
+
+
+class Solution:
+    def countBits(self, n: int) -> List[int]:
+        dp = [0] * (n + 1)
+
+        for i in range(1, n + 1):
+            dp[i] = dp[i >> 1] + (i & 1)
+
+        return dp

house-robber-ii/pmjuu.py

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+'''
+시간 복잡도: O(n)
+공간 복잡도: O(n)
+'''
+from typing import List
+
+class Solution:
+    def rob(self, nums: List[int]) -> int:
+        n = len(nums)
+        if n == 1:
+            return nums[0]
+        if n == 2:
+            return max(nums[0], nums[1])
+
+        dp_first = [0] * n
+        dp_second = [0] * n
+
+        dp_first[0], dp_first[1] = nums[0], max(nums[0], nums[1])
+        dp_second[1], dp_second[2] = nums[1], max(nums[1], nums[2])
+
+        for i in range(2, n):
+            dp_first[i] = max(dp_first[i - 1], dp_first[i - 2] + nums[i])
+            dp_second[i] = max(dp_second[i - 1], dp_second[i - 2] + nums[i])
+
+        return max(dp_first[-2], dp_second[-1])