49. Group Anagrams

Problem:

Given an array of strings, group anagrams together.

Example:

Input: ["eat", "tea", "tan", "ate", "nat", "bat"],
Output:
[
  ["ate","eat","tea"],
  ["nat","tan"],
  ["bat"]
]

Note:

• All inputs will be in lowercase.
• The order of your output does not matter.

Solution:

It’s all about hashing the words.

ONE

Sort each word to get the key.

/**
 * @param {string[]} strs
 * @return {string[][]}
 */
let groupAnagrams = function(strs) {
  let result = {};
  for (let i = 0; i < strs.length; i++) {
    const hash = strs[i].split('').sort().join('');
    result[hash] = result[hash] || []
    result[hash].push(strs[i])
  }
  return Object.values(result)
};

TWO

Use the product of prime numbers to generate unique keys.

const prime = [2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101]

/**
 * @param {string[]} strs
 * @return {string[][]}
 */
let groupAnagrams = function(strs) {
  const result = {};
  for (let i = 0; i < strs.length; i++) {
    const word = strs[i]
    let hash = 1
    for (let k = 0; k < word.length; k++) {
      hash *= prime[word.charCodeAt(k) - 97]
    }
    result[hash] = result[hash] || []
    result[hash].push(word)
  }
  return Object.values(result)
};

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