0535-encode-and-decode-tinyurl.js

/**
 * 535. Encode and Decode TinyURL
 * https://leetcode.com/problems/encode-and-decode-tinyurl/
 * Difficulty: Medium
 *
 * TinyURL is a URL shortening service where you enter a URL such as
 * https://leetcode.com/problems/design-tinyurl and it returns a short URL such as
 * http://tinyurl.com/4e9iAk. Design a class to encode a URL and decode a tiny URL.
 *
 * There is no restriction on how your encode/decode algorithm should work. You just
 * need to ensure that a URL can be encoded to a tiny URL and the tiny URL can be
 * decoded to the original URL.
 *
 * Implement the Solution class:
 * - Solution() Initializes the object of the system.
 * - String encode(String longUrl) Returns a tiny URL for the given longUrl.
 * - String decode(String shortUrl) Returns the original long URL for the given shortUrl.
 *   It is guaranteed that the given shortUrl was encoded by the same object.
 */

const map = new Map();
let counter = 1;

/**
 * Encodes a URL to a shortened URL.
 *
 * @param {string} longUrl
 * @return {string}
 */
var encode = function(longUrl) {
  const shortUrl = 'https://tinyurl.com/' + counter.toString();
  map.set(shortUrl, longUrl);
  counter++;
  return shortUrl;
};

/**
 * Decodes a shortened URL to its original URL.
 *
 * @param {string} shortUrl
 * @return {string}
 */
var decode = function(shortUrl) {
  return map.get(shortUrl) || null;
};