Create 104-max_depth_of_binary_tree.py

Author: stevestar888

104-max_depth_of_binary_tree.py

@@ -0,0 +1,51 @@
+"""
+https://leetcode.com/problems/maximum-depth-of-binary-tree/
+
+Strat:
+    Do this problem recursively. You might think you need a helper,
+    but you can do without!
+
+Runtime: O(n) time, O(1) space -- doing a DFS traversal, where you visit every node once + no DS
+    28 ms	15.6 MB	
+"""
+
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution(object):
+    def maxDepth(self, root):
+        """
+        :type root: TreeNode
+        :rtype: int
+        """
+        if root == None: 
+            return 0
+        
+        left = self.maxDepth(root.left)
+        right = self.maxDepth(root.right)
+        
+        return max(left, right) + 1
+
+    ### Original thought:
+#     def maxDepth(self, root):
+#         """
+#         :type root: TreeNode
+#         :rtype: int
+#         """
+#         return self.helper(root, 0)
+        
+#     def helper(self, root, max_depth):        
+#         #base case
+#         if root == None:
+#             return max_depth
+
+#         #found a known node, increase depth
+#         max_depth += 1
+
+#         left = self.helper(root.left, max_depth)
+#         right = self.helper(root.right, max_depth)
+
+#         return max(left, right)