Given a root of an N-ary tree, you need to compute the length of the diameter of the tree. The diameter of an N-ary tree is the length of the longest path between any two nodes in the tree. This path may or may not pass through the root. (Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value.) Example 1: Input: root = [1,null,3,2,4,null,5,6] Output: 3 Explanation: Diameter is shown in red color. Example 2: Input: root = [1,null,2,null,3,4,null,5,null,6] Output: 4 Example 3: Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14] Output: 7 Constraints: The depth of the n-ary tree is less than or equal to 1000. The total number of nodes is between [1, 104].