LeetCode 535 Encode and Decode TinyURL (HashMap)

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.

题目链接：https://leetcode.com/problems/encode-and-decode-tinyurl/#/description

题目分析：按长度最短字典序递增的方式构造TinyURL

击败77.5%

public class Codec {        HashMap<String, String> dec = new HashMap<>();    HashMap<String, String> enc = new HashMap<>();    public String getNext(String cur) {        String code = enc.get(cur);        if (code == null) {            return "0";        }        int len = code.length();        char ch = code.charAt(len - 1);        String ans = "";        if (ch == '9') {            ans = code.substring(0, len - 1) + 'Z';        }        else if (ch == 'Z') {            ans = code.substring(0, len - 1) + 'z';        }        else if (ch == 'z') {            ans = code + '0';        } else {            ans = code.substring(0, len - 2) + (code.charAt(len - 1) + 1);        }        return ans;    }    // Encodes a URL to a shortened URL.    public String encode(String longUrl) {        String shortUrl = getNext(longUrl);        enc.put(longUrl, shortUrl);        dec.put(shortUrl, longUrl);        return shortUrl;    }    // Decodes a shortened URL to its original URL.    public String decode(String shortUrl) {        return dec.get(shortUrl);    }}// Your Codec object will be instantiated and called as such:// Codec codec = new Codec();// codec.decode(codec.encode(url));