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.
Solution：Map(id -> url)
思路：
最簡單的一種編碼就是用個計數(shù)器倍权，當前是第幾個存入的url就編碼成幾侵蒙，然后解碼的時候也能根據(jù)數(shù)字來找到原來的url
Time Complexity: O(N) Space Complexity: O(N)
Solution Code：
public class Codec {
List<String> urls = new ArrayList<String>();
// Encodes a URL to a shortened URL.
public String encode(String longUrl) {
urls.add(longUrl);
return String.valueOf(urls.size()-1);
}
// Decodes a shortened URL to its original URL.
public String decode(String shortUrl) {
int index = Integer.valueOf(shortUrl);
return (index<urls.size())?urls.get(index):"";
}
}
