How should I practice Vertical Tree Traversal with Value Ties?

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

Is Vertical Tree Traversal with Value Ties associated with Meta?

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

Vertical Tree Traversal with Value Ties

Meta● HardINTERNPHONE SCREEN

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Problem statement

Return the vertical traversal of a binary tree. The root is at (row,column) = (0,0). A left child moves to (row+1,column-1), and a right child to (row+1,column+1).

Return columns from leftmost to rightmost. Within a column, order nodes by increasing row. When multiple nodes share both row and column, order their values increasingly.

Function

verticalTraversal(root: TreeNode) → int[][]

Examples

Example 1

root = [3,9,20,null,null,15,7]return = [[9],[3,15],[20],[7]]

Columns appear from leftmost to rightmost, with row order inside each column.

Example 2

root = [1,2,3,4,5,6,7]return = [[4],[2],[1,5,6],[3],[7]]

Values5 and6 share row and column, so5 comes first.

Example 3

root = [1,2,3,4,6,5,7]return = [[4],[2],[1,5,6],[3],[7]]

Swapping the two shared-coordinate nodes does not change their sorted output.

Constraints

The tree contains between 1 and 1000 nodes.
0 <= Node.val <= 1000.