Create 543_Diameter_Of_Binary_Tree.py

Python/543_Diameter_Of_Binary_Tree.py

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+'''
+Given the root of a binary tree, return the length of the diameter of the tree.
+The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root.
+The length of a path between two nodes is represented by the number of edges between them.
+'''
+# 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
+class Solution:
+    def diameterOfBinaryTree(self, root: TreeNode) -> int:
+        def diameterTreeUtil(root):
+            if root == None: return [0,0]
+
+            leftTree = diameterTreeUtil(root.left)
+            rightTree = diameterTreeUtil(root.right)
+
+            internalPath = max(leftTree[1],rightTree[1])
+            if leftTree[0] + rightTree[0] + 1 > internalPath: internalPath = leftTree[0] + rightTree[0] + 1
+
+            return [max(leftTree[0],rightTree[0])+1,internalPath]
+
+        if root == None: return 0
+        result = diameterTreeUtil(root)
+        return max(result)-1