Group Anagrams Using Hash Map in DSA C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an anagram?

An anagram is a word or phrase formed by rearranging the letters of another word or phrase, using all the original letters exactly once.

beginner

Why do we use a hash map to group anagrams?

A hash map helps group anagrams by using a key that represents the sorted letters of a word. Words with the same sorted key are anagrams and get grouped together.

beginner

How do you create a key for each word to group anagrams?

Sort the letters of the word alphabetically. The sorted string is used as the key in the hash map.

intermediate

What is the time complexity of grouping anagrams using a hash map?

The time complexity is O(N * K log K), where N is the number of words and K is the maximum length of a word (due to sorting each word).

beginner

What data structure stores the grouped anagrams in the hash map?

Each key in the hash map points to a list (or array) of words that are anagrams of each other.

What is the key used in the hash map to group anagrams?

A The length of the word

B The first letter of the word

C The sorted version of the word

D The original word itself

The sorted version of the word is used as the key because all anagrams share the same sorted letters.

Which data structure is best to store groups of anagrams?

A Binary tree

B Stack

C Queue

D Hash map with list values

A hash map with lists as values allows grouping words by their sorted key efficiently.

What is the main operation done on each word before inserting into the hash map?

A Sorting the letters

B Reversing the word

C Counting vowels

D Converting to uppercase

Sorting the letters creates a uniform key for all anagrams.

If two words have the same sorted key, what does it mean?

A They are anagrams

B They have the same length

C They start with the same letter

D They are identical

Same sorted key means the words contain the same letters in the same frequency, so they are anagrams.

What is the main benefit of using a hash map for grouping anagrams?

A Sorting all words at once

B Fast lookup and grouping by key

C Reducing word length

D Avoiding sorting

Hash maps provide fast insertion and lookup, making grouping efficient.

Explain how to group a list of words into anagrams using a hash map.

Think about how sorting helps identify anagrams.

Describe the role of sorting in the 'Group Anagrams Using Hash Map' algorithm.

Focus on why sorting is done before grouping.