How should I practice Flatten Binary Tree to Linked List?

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

Is Flatten Binary Tree to Linked List 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.

Flatten Binary Tree to Linked List

Bloomberg LP● MediumNEW GRADPHONE SCREEN

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Problem statement

Flatten the binary tree rooted at root in place into a right-child-only chain whose node order is the tree's preorder traversal. Set every left child to null and return root.

Function

flattenTree(root: TreeNode) → TreeNode

Examples

Example 1

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

The right chain follows preorder 1,2,3,4,5,6.

Constraints

The tree contains at most 2000 nodes.
Node values fit in signed 32-bit integers.