Lunski's Clutter

Given two integer arrays preorder and inorder where preorder is the preorder traversal of a binary tree and inorder is the inorder traversal of the same tree, construct and return the binary tree.

Example 1:

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Input: preorder = [3,9,20,15,7], inorder = [9,3,15,20,7]
Output: [3,9,20,null,null,15,7]

Example 2:

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Input: preorder = [-1], inorder = [-1]
Output: [-1]

Given a binary tree, collect a tree’s nodes as if you were doing this: Collect and remove all leaves, repeat until the tree is empty.

Example:

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Input: [1,2,3,4,5]
  
          1
         / \
        2   3
       / \     
      4   5    

Output: [[4,5,3],[2],[1]]

Explanation:

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1. Removing the leaves [4,5,3] would result in this tree:

          1
         / 
        2          
 

2. Now removing the leaf [2] would result in this tree:

          1          
 

3. Now removing the leaf [1] would result in the empty tree:

          []        

Given the root of a binary tree, return its maximum depth.

A binary tree’s maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Example 1:

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Input: root = [3,9,20,null,null,15,7]
Output: 3

Example 2:

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Input: root = [1,null,2]
Output: 2

Example 3:

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Input: root = []
Output: 0

Example 4:

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Input: root = [0]
Output: 1

Given the root of a binary tree, return the level order traversal of its nodes’ values. (i.e., from left to right, level by level).

Example 1:

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Input: root = [3,9,20,null,null,15,7]
Output: [[3],[9,20],[15,7]]

Example 2:

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Input: root = [1]
Output: [[1]]

Example 3:

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Input: root = []
Output: []

Given the roots of two binary trees p and q, write a function to check if they are the same or not.

Two binary trees are considered the same if they are structurally identical, and the nodes have the same value.

Example 1:

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Input: p = [1,2,3], q = [1,2,3]
Output: true

Example 2:

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Input: p = [1,2], q = [1,null,2]
Output: false

Example 3:

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Input: p = [1,2,1], q = [1,1,2]
Output: false