How should I practice Group Rotation-Equivalent Strings?

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

Is Group Rotation-Equivalent Strings associated with Google?

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

Group Rotation-Equivalent Strings

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Problem statement

Given a list of strings, group strings that can be converted into each other by rotating characters. A rotation moves any prefix to the end, preserving the character order.

For this exercise, assume strings contain lowercase ASCII letters and may be empty. Return all groups in the order their first member appears in the input. Within each group, keep the original input order and retain duplicate entries. Empty strings are rotation-equivalent to each other. Rotation never changes string length; anagrams with a different cyclic order belong to different groups.

Function

groupRotations(words: String[]) → String[][]

Examples

Example 1

words = ["abc","bca","cab","xyz"]return = [["abc","bca","cab"],["xyz"]]

The source example groups abc, bca and cab; xyz forms a separate group.

Example 2

words = ["xyz","cab","zxy","abc","bca"]return = [["xyz","zxy"],["cab","abc","bca"]]

The xyz group appears first because its first member occurs first. Every group keeps input member order.

Example 3

words = ["","","a","a","aa"]return = [["",""],["a","a"],["aa"]]

Empty strings and repeated entries are preserved; a and aa are not rotations of each other.

Constraints

For this exercise, assume 0 <= words.length <= 200.
Each string has at most 100 lowercase ASCII letters.
The sum of string lengths is at most 2000.