day_11.py

'''
Problem Statement:
Given a binary tree, you need to compute 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.

Example:
Given a binary tree
          1
         / \
        2   3
       / \     
      4   5    
Return 3, which is the length of the path [4,2,1,3] or [5,2,1,3].

Note: The length of path between two nodes is represented by the number of edges between them.
'''
#Solution:

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def diameterOfBinaryTree(self, root: TreeNode) -> int:
        self.temp = 1
        def height(node):
            if not node:
                return 0
            L = height(node.left)
            R = height(node.right)
            
            self.temp = max(self.temp,L+R+1)
            return max(L,R) + 1
        height(root)
        return self.temp - 1