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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