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543. Diameter Of Binary Tree

Tree Depth-First Search Binary Tree

Problem - Diameter Of Binary Tree

Easy

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.

 

Example 1:

Input: root = [1,2,3,4,5]
Output: 3
Explanation: 3 is the length of the path [4,2,1,3] or [5,2,1,3].

Example 2:

Input: root = [1,2]
Output: 1

 

Constraints:

  • The number of nodes in the tree is in the range [1, 104].
  • -100 <= Node.val <= 100

Solutions

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# 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: Optional[TreeNode]) -> int:
        result = 0
        def dfs(root):
            if root is None:
                return 0
            left, right = dfs(root.left), dfs(root.right)
            nonlocal result
            result = max(result, left + right)

            return max(left, right) + 1

        dfs(root)
        return result

Submission Stats:

  • Runtime: 0 ms (100.00%)
  • Memory: 20.7 MB (84.05%)