update readme

Author: hogan-tech

0104-maximum-depth-of-binary-tree/0104-maximum-depth-of-binary-tree.py

@@ -1,17 +1,67 @@
-# 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
+# time complexity: O(n)
+# space complexity: O(logn)
+from typing import Optional
+
+
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+
 class Solution:
     def maxDepth(self, root: Optional[TreeNode]) -> int:
-
         def longestPath(node: Optional[TreeNode]):
             if not node:
                 return 0
             leftPath = longestPath(node.left)
             rightPath = longestPath(node.right)
             return max(leftPath, rightPath)+1
+        return longestPath(root)
+
+
+# time complexity: O(n)
+# space complexity: O(n)
+class Solution:
+    def __init__(self):
+        self.nextItem = []
+        self.maxDepth = 0
+
+    def nextMaxDepth(self):
+        if not self.nextItem:
+            return self.maxDepth
+        nextNode, nextLvl = self.nextItem.pop(0)
+        nextLvl += 1
+        self.maxDepth = max(self.maxDepth, nextLvl)
+        if nextNode.left:
+            self.nextItem.append((nextNode.left, nextLvl))
+        if nextNode.right:
+            self.nextItem.append((nextNode.right, nextLvl))
+        return self.nextMaxDepth()
+
+    def maxDepth(self, root):
+        if not root:
+            return 0
+        self.nextItem = []
+        self.maxDepth = 0
+        self.nextItem.append((root, 0))
+        return self.nextMaxDepth()
+
+# time complexity: O(n)
+# space complexity: O(n)
+class Solution:
+    def maxDepth(self, root: TreeNode) -> int:
+        stack = []
+        if root is not None:
+            stack.append((1, root))
+
+        depth = 0
+        while stack != []:
+            currDepth, root = stack.pop()
+            if root is not None:
+                depth = max(depth, currDepth)
+                stack.append((currDepth + 1, root.left))
+                stack.append((currDepth + 1, root.right))
 
-        return longestPath(root)
+        return depth

0104-maximum-depth-of-binary-tree/README.md

@@ -115,39 +115,3 @@ It helps others discover the repo and keeps the project growing.
 ---
 
 Feedback / Questions → open an Issue or reach out on [LinkedIn](https://www.linkedin.com/in/hogan-l/)  
-
-<!---LeetCode Topics Start-->
-# LeetCode Topics
-## Tree
-|  |
-| ------- |
-| [0104-maximum-depth-of-binary-tree](https://github.com/hogan-tech/leetcode-solution/tree/master/0104-maximum-depth-of-binary-tree) |
-## Depth-First Search
-|  |
-| ------- |
-| [0104-maximum-depth-of-binary-tree](https://github.com/hogan-tech/leetcode-solution/tree/master/0104-maximum-depth-of-binary-tree) |
-## Breadth-First Search
-|  |
-| ------- |
-| [0104-maximum-depth-of-binary-tree](https://github.com/hogan-tech/leetcode-solution/tree/master/0104-maximum-depth-of-binary-tree) |
-## Binary Tree
-|  |
-| ------- |
-| [0104-maximum-depth-of-binary-tree](https://github.com/hogan-tech/leetcode-solution/tree/master/0104-maximum-depth-of-binary-tree) |
-## Hash Table
-|  |
-| ------- |
-| [0768-partition-labels](https://github.com/hogan-tech/leetcode-solution/tree/master/0768-partition-labels) |
-## Two Pointers
-|  |
-| ------- |
-| [0768-partition-labels](https://github.com/hogan-tech/leetcode-solution/tree/master/0768-partition-labels) |
-## String
-|  |
-| ------- |
-| [0768-partition-labels](https://github.com/hogan-tech/leetcode-solution/tree/master/0768-partition-labels) |
-## Greedy
-|  |
-| ------- |
-| [0768-partition-labels](https://github.com/hogan-tech/leetcode-solution/tree/master/0768-partition-labels) |
-<!---LeetCode Topics End-->

Python/0104-maximum-depth-of-binary-tree.py

@@ -1,17 +1,19 @@
-<h2><a href="https://leetcode.com/problems/maximum-depth-of-binary-tree/">104. Maximum Depth of Binary Tree</a></h2><h3>Easy</h3><hr><div><p>Given the <code>root</code> of a binary tree, return <em>its maximum depth</em>.</p>
+<h2><a href="https://leetcode.com/problems/maximum-depth-of-binary-tree">104. Maximum Depth of Binary Tree</a></h2><h3>Easy</h3><hr><p>Given the <code>root</code> of a binary tree, return <em>its maximum depth</em>.</p>
 
-<p>A binary tree's <strong>maximum depth</strong>&nbsp;is the number of nodes along the longest path from the root node down to the farthest leaf node.</p>
+<p>A binary tree&#39;s <strong>maximum depth</strong>&nbsp;is the number of nodes along the longest path from the root node down to the farthest leaf node.</p>
 
 <p>&nbsp;</p>
 <p><strong class="example">Example 1:</strong></p>
-<img alt="" src="https://assets.leetcode.com/uploads/2020/11/26/tmp-tree.jpg" style="width: 400px; height: 277px;">
-<pre><strong>Input:</strong> root = [3,9,20,null,null,15,7]
+<img alt="" src="https://assets.leetcode.com/uploads/2020/11/26/tmp-tree.jpg" style="width: 400px; height: 277px;" />
+<pre>
+<strong>Input:</strong> root = [3,9,20,null,null,15,7]
 <strong>Output:</strong> 3
 </pre>
 
 <p><strong class="example">Example 2:</strong></p>
 
-<pre><strong>Input:</strong> root = [1,null,2]
+<pre>
+<strong>Input:</strong> root = [1,null,2]
 <strong>Output:</strong> 2
 </pre>
 
@@ -22,4 +24,3 @@
 	<li>The number of nodes in the tree is in the range <code>[0, 10<sup>4</sup>]</code>.</li>
 	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
 </ul>
-</div>