Diameter of a Binary Tree

Problem Statement

You are given a binary tree and need to find the diameter length of the tree. The diameter is defined as the length of the longest path between any two nodes in the tree. This path can pass through or bypass the root node.

Examples

Consider the binary tree shown below:

           10
          /  \
         7    8
        / \
       4   5
    

The diameter length is 3, which corresponds to the path [4,7,10,8] or [5,7,10,8].

Another example:

           3
            \
             9
              \
               15
              /  \
             20   7
    

The diameter length here is 4, with the longest path being [20,15,9,3] or [7,15,9,3].

Constraints

• Number of nodes in the tree is between 1 and 20,000.
• Node values are integers ranging from -1,000,000 to 1,000,000.