Binary Tree Level Order Traversal

Given the root of a binary tree, return the node values grouped by level from top to bottom and left to right. If the tree is empty, return an empty list.

Inputroot = [3,9,20,null,null,15,7]Output[[3],[9,20],[15,7]]WhyEach level is collected separately.

Inputroot = [1]Output[[1]]WhyA single node forms one level.

Problem

Given the root of a binary tree, return the node values grouped by level from top to bottom and left to right. If the tree is empty, return an empty list.

Examples

Example 1

Inputroot = [3,9,20,null,null,15,7]Output[[3],[9,20],[15,7]]WhyEach level is collected separately.

Example 2

Inputroot = [1]Output[[1]]WhyA single node forms one level.

Constraints

0 <= number of nodes <= 2000
-1000 <= Node.val <= 1000
The input tree is a valid binary tree

Problem

Given the root of a binary tree, return the node values grouped by level from top to bottom and left to right. If the tree is empty, return an empty list.

Examples

Example 1

Inputroot = [3,9,20,null,null,15,7]Output[[3],[9,20],[15,7]]WhyEach level is collected separately.

Example 2

Inputroot = [1]Output[[1]]WhyA single node forms one level.

Constraints

0 <= number of nodes <= 2000
-1000 <= Node.val <= 1000
The input tree is a valid binary tree

Problem

Given the root of a binary tree, return the node values grouped by level from top to bottom and left to right. If the tree is empty, return an empty list.

Examples

Example 1

Inputroot = [3,9,20,null,null,15,7]Output[[3],[9,20],[15,7]]WhyEach level is collected separately.

Example 2

Inputroot = [1]Output[[1]]WhyA single node forms one level.

Constraints

0 <= number of nodes <= 2000
-1000 <= Node.val <= 1000
The input tree is a valid binary tree

Interview Guides

Problem

Examples

Constraints

Problem

Examples

Constraints

Binary Tree Level Order Traversal

Problem

Examples

Constraints

Problem

Examples

Constraints