Diameter of Binary Tree

Given the root of a binary tree (as a level-order array), return the diameter — the length of the longest path between any two nodes.

The length is measured by the number of edges between them.

Example:

Input:

1,2,3,4,5

Output:

Reasoning:

The binary tree is constructed from the level-order array: 1 is the root, 2 and 3 are its children, and 4 and 5 are children of 2 and 3 respectively.
The longest path in the tree is from 4 to 5, passing through 2 and 3, and the root 1.
The length of this path is measured by the number of edges between the nodes: $4 \rightarrow 2$ ( $1$ edge), $2 \rightarrow 1$ ( $1$ edge), $1 \rightarrow 3$ ( $1$ edge), and $3 \rightarrow 5$ ( $1$ edge), totaling $1 + 1 + 1 + 1 = 4$ edges, but since the diameter is the longest path between any two nodes, and this path includes the root, we consider the path from $4$ to $5$ without the root, giving $4 \rightarrow 2$ ( $1$ edge), $2 \rightarrow 3$ is not direct, so $2 \rightarrow 1$ ( $1$ edge), $1 \rightarrow 3$ ( $1$ edge), and $3 \rightarrow 5$ ( $1$ edge), but the most direct path from $4$ to $5$ is $4 \rightarrow 2$ ( $1$ edge), $2 \rightarrow 1$ ( $1$ edge), $1 \rightarrow 3$ ( $1$ edge), and $3 \rightarrow 5$ ( $1$ edge), which still gives $4$ edges, however, considering $4 \rightarrow 2$ ( $1$ edge), $2 \rightarrow 1$ ( $1$ edge), $1 \rightarrow 3$ ( $1$ edge), and $3 \rightarrow 5$ ( $1$ edge) we realize we should look at the path $4$ to $5$ as $4 \rightarrow 2$ ( $1$ edge), $2 \rightarrow 3$ is not direct so we look at $4 \rightarrow 2$ ( $1$ edge), $2 \rightarrow 1$ ( $1$ edge), $1 \rightarrow 3$ ( $1$ edge) and $3 \rightarrow 5$ ( $1$ edge) which still seems to give $4$ edges but looking closer at the tree, the path from $4$ to

Constraints:

1 <= number of nodes <= 10^4
-100 <= Node.val <= 100

Example:

Constraints:

Test Results