How should I practice Decode a Binary Tree by Vertical Traversal?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Bloomberg LP phone screen problems in FastPrep.

Is Decode a Binary Tree by Vertical Traversal associated with Bloomberg LP?

FastPrep tags this as a Bloomberg LP phone screen coding practice problem when the problem catalog has that company and stage context.

Decode a Binary Tree by Vertical Traversal

Bloomberg LP● MediumNEW GRADPHONE SCREEN

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Problem statement

Each node value is the ASCII code of a lowercase letter. Give root column 0, left child column-1, and right child column+1. Read columns from smallest to largest; within a column read top-to-bottom, breaking same-row ties by left-to-right BFS discovery.

Concatenate the letters and return the decoded string.

Function

decodeVerticalTree(root: TreeNode) → String

Examples

Example 1

root = [114,101,116,null,null,101,null,99,null,115]return = "secret"

Columns spell s, ec, re, t from left to right.

Constraints

The tree contains at most 10^5 nodes.
Values are ASCII codes 97 through 122.