Given a binary tree, you need to compute the length of the tree’s diameter. 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.

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

Constraints:

• The number of nodes in the tree is in the range $[1, 500]$.
• $-100 \leq$ Node.value $\leq 100$