Wavefront Tree Scan (Hard)

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Wavefront Tree Scan

Hard

Trees

In "Wavefront Tree Scan", the binary tree is provided in array form (level-order with null gaps).

Return node values grouped by depth from top to bottom and left to right.

Example 1

Input:root = [16,17,18,null,19,20,null]

Output:[[16],[17,18],[19,20]]

For input root = [16,17,18,null,19,20,null], nodes are grouped by depth from top to bottom, yielding [[16],[17,18],[19,20]]. Therefore, return [[16],[17,18],[19,20]].

Example 2

Input:root = [26,27,28,29,null,null,30]

Output:[[26],[27,28],[29,30]]

For input root = [26,27,28,29,null,null,30], nodes are grouped by depth from top to bottom, yielding [[26],[27,28],[29,30]]. Therefore, return [[26],[27,28],[29,30]].

Constraints

0 <= number of nodes <= 2000
-1000 <= Node.val <= 1000

solution.js

Test Cases (2)

Test Case 1

Input:

[16,17,18,null,19,20,null]

Expected Output:

[[16],[17,18],[19,20]]

Test Case 2

Input:

[26,27,28,29,null,null,30]

Expected Output:

[[26],[27,28],[29,30]]