Hello,\n\nsome probelms with linked lists like this one: https://leetcode.com/problems/binary-tree-inorder-traversal/\n\nhave an example input-output case where the input is represented as an array. \n\nInput: root = [1,null,2,3]\nOutput: [1,3,2]\n\nI don\'t understand how the array is formed. Is this some javascript standard of printing linked lists, or is it just a representation that I should understand? I would like it to be explained somewhere. Why is it [1, null, 2, 3] ?

Hello,\n\nsome probelms with linked lists like this one: https://leetcode.com/problems/binary-tree-inorder-traversal/\n\nhave an example input-output case where