encode-and-decode-tinyurl.java

// 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 a class to encode a URL and decode a tiny URL.
//
// 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.
//
// Implement the Solution class:
//
//
// 	Solution() Initializes the object of the system.
// 	String encode(String longUrl) Returns a tiny URL for the given longUrl.
// 	String decode(String shortUrl) Returns the original long URL for the given shortUrl. It is guaranteed that the given shortUrl was encoded by the same object.
//
//
//  
// Example 1:
//
//
// Input: url = "https://leetcode.com/problems/design-tinyurl"
// Output: "https://leetcode.com/problems/design-tinyurl"
//
// Explanation:
// Solution obj = new Solution();
// string tiny = obj.encode(url); // returns the encoded tiny url.
// string ans = obj.decode(tiny); // returns the original url after deconding it.
//
//
//  
// Constraints:
//
//
// 	1 <= url.length <= 104
// 	url is guranteed to be a valid URL.
//
//


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 ind = Integer.valueOf(shortUrl);
        return (ind<urls.size())?urls.get(ind):"";
    }
}

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