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49-Group-Anagrams.js
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49-Group-Anagrams.js
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//////////////////////////////////////////////////////////////////////////////
// Hash Each Word
// Time: O(n*max(w))
// Space: O(n*max(w))
// This solution is faster than sorting each word.
//////////////////////////////////////////////////////////////////////////////
/**
* @param {string[]} words
* @return {string[][]}
*/
function groupAnagrams(words) {
const map = Object.create(null);
for (const word of words) {
const hash = hashWord(word);
if (!(hash in map)) {
map[hash] = [];
}
map[hash].push(word);
}
const groups = [];
for (const key in map) {
groups.push(map[key]);
}
return groups;
}
/**
* @param {string} word
* @return {string}
*/
function hashWord(word) {
const hash = new Array(26).fill(0);
for (const ch of word) {
++hash[ch.charCodeAt(0) - 'a'.charCodeAt(0)];
}
return hash.toString();
}
//////////////////////////////////////////////////////////////////////////////
// Sort Each Word
// Time: O(n*max(w)*log(max(w)))
// Space: O(n*max(w))
// This solution is slower than hashing each word.
//////////////////////////////////////////////////////////////////////////////
/**
* @param {string[]} strs
* @return {string[][]}
*/
const groupAnagrams = (strs) => {
const result = [];
const map = new Map();
for (let i = 0; i < strs.length; i++) {
const sorted = strs[i].split('').sort().join('');
//! we are just splitting the string and sorting it and joining it back
if (map.has(sorted)) {
map.get(sorted).push(strs[i]); //! if the map has the sorted string, we push the string into the array
} else {
map.set(sorted, [strs[i]]); //! we are pushing the string into the map with the sorted string as the key
}
}
for (let [key, value] of map) {
result.push(value);
}
return result;
};