Group Anagrams

Problem Given a list of strings, group together the ones that are anagrams of each other — strings with the same multiset of characters, regardless of order.

Input / Output

• Input: an array of strings words (lowercase English letters).
• Output: a list of groups, each containing all mutual anagrams. Group order and within-group order are unconstrained.

Constraints

• 1 ≤ n ≤ 10^4.
• Each string up to ~100 characters.

Example

• ["eat","tea","tan","ate","nat","bat"] → [["eat","tea","ate"],["tan","nat"],["bat"]].
• Single-character and empty strings each group only with exact duplicates.