解法一

计数作为编码。

  1. public class Codec {
  2.     private Map<Integer, String> map;
  3.     private int index;
  4.     public Codec() {
  5.         map = new HashMap<>();
  6.         index = 0;
  7.     }
  8.     // Encodes a URL to a shortened URL.
  9.     public String encode(String longUrl) {
  10.         map.put(index, longUrl);
  11.         return "http://tinyurl.com/" + index++;
  12.     }
  14.     // Decodes a shortened URL to its original URL.
  15.     public String decode(String shortUrl) {
  16.         return map.get(Integer.parseInt(shortUrl.substring(19, shortUrl.length())));
  17.     }
  18. }
  20. // Your Codec object will be instantiated and called as such:
  21. // Codec codec = new Codec();
  22. // codec.decode(codec.encode(url));