535. Encode and Decode TinyURL-优快云博客

本文详细介绍了TinyURL服务的设计与实现过程，通过编码长URL为短URL并能准确解码回原URL，采用hashcode作为索引存储在hashmap中，确保了URL的唯一性和快速检索，时间复杂度为O(1)，空间复杂度为O(n)。

问题描述

Note: This is a companion problem to the System Design problem: Design TinyURL.
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：

思路分析

给一个长Url，要能把它编码为短Url，并且能再解码回来。一般采用的方式是存在hashmap中，我选择使用hashcode作为索引。

代码

public class Codec {
    Map<Integer, String> map  = new HashMap<>();
    // Encodes a URL to a shortened URL.
    public String encode(String longUrl) {
        map.put(longUrl.hashCode(), longUrl);
        return "http://tinyurl.com/" + longUrl.hashCode();
    }

    // Decodes a shortened URL to its original URL.
    public String decode(String shortUrl) {
        return map.get(Integer.parseInt(shortUrl.replace("http://tinyurl.com/", "")));
    }
}

// Your Codec object will be instantiated and called as such:
// Codec codec = new Codec();
// codec.decode(codec.encode(url));