RWC: Group Anagrams

group-anagrams.js

/**
 * Take an array of phrases and return a list of anagram groups
 * @param {string[]} phrases list of strings which may or may not be anagrams of other strings in the same list
 * @returns {string[][]} a list of arrays of strings, where every string in an inner array is an anagram of the others
 */
function groupAnagrams(phrases) {
	/** @type {Object<string, string[]>} */
	const anagramGroups = {};

	// Create a map of anagram groups
	for (const phrase of phrases) {
		const sortedLetters = phrase
			.toLowerCase()				// Capitalization doesn't matter for anagrams
			.replace(/[^a-z]/g, '')		// Remove any character that isn't a letter
			.split('')					// Convert to an array of letters
			.sort()						// Arrange those letters alphabetically
			.join('');					// Make it a string again


		if (anagramGroups[sortedLetters]) {
			anagramGroups[sortedLetters].push(phrase);
		} else {
			anagramGroups[sortedLetters] = [phrase];
		}
	}

	return [...Object.values(anagramGroups)];
}

const groups = groupAnagrams(['eat', 'tea', 'ten', 'poop', 'net', 'ate']);
console.log(groups);