added construct string from tree

david-legend · david-legend · commit 8af9825242ee · 2022-09-09T13:11:37.000Z
diff --git a/leetcode/src/binary_trees/lc_543_diameter_of_a_tree/tree_diameter.py b/leetcode/src/binary_trees/lc_543_diameter_of_a_tree/tree_diameter.py
@@ -2,4 +2,23 @@ class TreeNode:
     def __init__(self, val=0, left=None, right=None):
         self.val = val
         self.left = left
-        self.right = right
+        self.right = right
+
+
+def tree_diameter(root):
+    def tree_diameter_helper(node):
+        nonlocal diameter
+        if node is None:
+            return 0
+        
+        left = tree_diameter_helper(node.left)
+        right = tree_diameter_helper(node.right)
+
+        diameter = max(diameter, left + right)
+
+        return max(left, right) + 1
+
+    diameter = 0
+    tree_diameter_helper(root)
+
+    return diameter
diff --git a/leetcode/src/binary_trees/lc_572_subtree_of_another_tree/README.md b/leetcode/src/binary_trees/lc_572_subtree_of_another_tree/README.md
@@ -2,7 +2,7 @@
 
 Given the roots of two binary trees root and subRoot, return true if there is a subtree of root with the same structure and node values of subRoot and false otherwise.  
 
-A subtree of a binary tree tree is a tree that consists of a node in tree and all of this node's descendants. The tree tree could also be considered as a subtree of itself.  
+A subtree of a binary tree is a tree that consists of a node in tree and all of this node's descendants. The tree could also be considered as a subtree of itself.  
 ### Example 1
 
 ![Subtree of Another Tree Example 1](https://assets.leetcode.com/uploads/2021/04/28/subtree1-tree.jpg)  
diff --git a/leetcode/src/binary_trees/lc_606_construct_string_from_tree/construct_string_from_tree.py b/leetcode/src/binary_trees/lc_606_construct_string_from_tree/construct_string_from_tree.py
@@ -0,0 +1,22 @@
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+def treeStr(root):
+    def treeStrHelper(node):
+        result = str(node.val)
+
+        if node.left:
+            result += "(" + treeStrHelper(node.left) + ")"
+        
+        if node.right:
+            if not node.left:
+                result += "()"
+            
+            result += "(" + treeStrHelper(node.right) + ")"
+        
+        return result
+
+    return treeStrHelper(root)
