[LC] feat: 240825 construct binary tree from preorder and inorder traversal

Author: HaJunYoo

construct-binary-tree-from-preorder-and-inorder-traversal/hajunyoo.py

@@ -0,0 +1,23 @@
+# Definition for a binary tree node.
+from typing import List
+
+
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+class Solution:
+    # time complexity: O(n)
+    # space complexity: O(n)
+    def buildTree(self, preorder: List[int], inorder: List[int]) -> Optional[TreeNode]:
+        if not preorder or not inorder:
+            return None
+
+        val = preorder.pop(0)
+        mid = inorder.index(val)
+        left = self.buildTree(preorder, inorder[:mid])
+        right = self.buildTree(preorder, inorder[mid + 1:])
+
+        return TreeNode(val, left, right)

encode-and-decode-strings/hajunyoo.py

@@ -1,27 +1,15 @@
 class Solution1:
-    """
-    @param: strs: a list of strings
-    @return: encodes a list of strings to a single string.
-    """
     # time complexity: O(n)
     # space complexity: O(1)
     def encode(self, strs):
         return ":;".join(strs)
 
-    """
-    @param: str: A string
-    @return: decodes a single string to a list of strings
-    """
     # time complexity: O(n)
     # space complexity: O(1)
     def decode(self, str):
         return str.split(":;")
 
 class Solution2:
-    """
-    @param: strs: a list of strings
-    @return: encodes a list of strings to a single string.
-    """
     # time complexity: O(n)
     # space complexity: O(1)
     def encode(self, strs):
@@ -30,10 +18,6 @@ def encode(self, strs):
             txt += str(len(s)) + ":" + s
         return txt
 
-    """
-    @param: str: A string
-    @return: decodes a single string to a list of strings
-    """
     # time complexity: O(n)
     # space complexity: O(1)
     def decode(self, str):