readme.md

Challenge: Anagram Grouping

Anagrams are words or phrases formed by rearranging the letters of another word or phrase. For example, cinema is an anagram of iceman.

Instructions

Write a function called anagramGrouping that takes an array of strings as input and returns an array of arrays, where each sub-array contains words that are anagrams of each other.

Function Signature

/**
 * Returns an array of arrays, where each sub-array contains words that are anagrams of each other.
 * @param {string[]} words - The input array of strings containing words.
 * @returns {string[][]} - The array of arrays with anagram groups.
 */
function anagramGrouping(words: string[]): string[][];

Examples

anagramGrouping(['cat', 'act', 'dog', 'god', 'tac']);
// Output: [['cat', 'act', 'tac'], ['dog', 'god']]

anagramGrouping(['listen', 'silent', 'enlist', 'hello', 'world']);
// Output: [['listen', 'silent', 'enlist'], ['hello'], ['world']]

Constraints

• The input array words will contain only lowercase alphabetical characters.

Hints

• You can use a map to store the anagram groups, where the key is the sorted characters of each word, and the value is an array of words that have the same sorted characters
• You can sort a string by splitting it into an array of chars and calling .sort() and then join() it back to a string
• You can use Array.from() to convert a map to an array

Solutions

Click For Solution

function anagramGrouping(words) {
  const anagramGroups = new Map();

  for (const word of words) {
    const sortedChars = word.split('').sort().join('');
    if (anagramGroups.has(sortedChars)) {
      anagramGroups.get(sortedChars).push(word);
    } else {
      anagramGroups.set(sortedChars, [word]);
    }
  }

  return Array.from(anagramGroups.values());
}

Explanation

• Create a new map anagramGroups to store the anagram groups.
• Iterate through each word in the input array words. For each word, split its characters into an array, sort the array in ascending order, and then join the sorted characters back into a string. This sorted string becomes the key for our anagramGroups map.
• Check if the key already exists in the map. If it does, retrieve the corresponding array and add the word to it.
• If the key does not exist in the map, create a new array with the word as the first element and add it to the map with the key.
• After processing all the words, extract the arrays of anagram groups from the anagramGroups map using Array.from(anagramGroups.values()) and return them as the final output.

Test Cases

test('Grouping anagrams', () => {
  const result1 = anagramGrouping(['cat', 'act', 'dog', 'god', 'tac']);
  const result2 = anagramGrouping([
    'listen',
    'silent',
    'enlist',
    'hello',
    'world',
  ]);

  expect(result1).toEqual([
    ['cat', 'act', 'tac'],
    ['dog', 'god'],
  ]);
  expect(result2).toEqual([
    ['listen', 'silent', 'enlist'],
    ['hello'],
    ['world'],
  ]);
});