package LeetCode_535 /** * 535. Encode and Decode TinyURL * https://leetcode.com/problems/encode-and-decode-tinyurl/description/ * * 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 the encode and decode methods for the TinyURL service. 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. * */ class Codec() { /* * solution, Two HaspMap * */ private val BASE_URL = "http://tinyurl.com/" //total 62 characters for generate short_url val chatSet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" //key is long url,value short url val mapShortUrl = HashMap<String, String>() //key is short url,value long url val mapLongUrl = HashMap<String, String>() // Encodes a URL to a shortened URL. fun encode(longUrl: String): String { if (mapShortUrl.containsKey(longUrl)) { return mapShortUrl.get(longUrl) ?: "" } var key = "" do { val sb = StringBuilder() for (i in 0..6) { val r = (Math.random() * chatSet.length).toInt() sb.append(chatSet[r]) } key = sb.toString() //if contains key, keep doing generate } while (mapShortUrl.containsKey(longUrl)) val url = BASE_URL + key mapShortUrl.put(longUrl, url) mapLongUrl.put(url, longUrl) return url } // Decodes a shortened URL to its original URL. fun decode(shortUrl: String): String { return mapLongUrl.getOrDefault(shortUrl, "") } } /** * Your Codec object will be instantiated and called as such: * var obj = Codec() * var url = obj.encode(longUrl) * var ans = obj.decode(url) */