Group Anagrams

L7 Medium Arrays & Hashing

Concept

The same sorted-letter key that identifies anagrams gives you the dictionary key to collect them into groups.

Given an array of strings strs, collect strings that are anagrams of each other into a single group and return all groups. The order of groups, and the order inside each group, does not matter.

Examples

▸ strs = ["eat", "tea", "tan", "ate", "nat", "bat"]

→ [["bat"], ["nat", "tan"], ["ate", "eat", "tea"]]

▸ strs = [""]

→ [[""]]

▸ strs = ["a"]

→ [["a"]]

Progressive Hints

Hint 1 · Nudge

Anagrams share the same sorted letters, so sorted letters make a perfect grouping key.

Hint 2 · Plan

For each word, sort its letters to build a key. Keep a dictionary mapping each key to a growing list, then return all the lists.

Hint 3 · Approach

groups = map from sorted-letters key to list. For each word: key = the word's letters sorted; append the word to groups[key]. Return the values of the dictionary.

Output

// Run your code to see the output here.