535. Encode and Decode TinyURL

Description

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 decoding it.

Constraints:

1 <= url.length <= 10⁴
url is guranteed to be a valid URL.

Solutions

Solution 1

Python3JavaC++Go

class Codec:
    def __init__(self):
        self.m = defaultdict()
        self.idx = 0
        self.domain = 'https://tinyurl.com/'

    def encode(self, longUrl: str) -> str:
        """Encodes a URL to a shortened URL."""
        self.idx += 1
        self.m[str(self.idx)] = longUrl
        return f'{self.domain}{self.idx}'

    def decode(self, shortUrl: str) -> str:
        """Decodes a shortened URL to its original URL."""
        idx = shortUrl.split('/')[-1]
        return self.m[idx]


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

public class Codec {
    private Map<String, String> m = new HashMap<>();
    private int idx = 0;
    private String domain = "https://tinyurl.com/";

    // Encodes a URL to a shortened URL.
    public String encode(String longUrl) {
        String v = String.valueOf(++idx);
        m.put(v, longUrl);
        return domain + v;
    }

    // Decodes a shortened URL to its original URL.
    public String decode(String shortUrl) {
        int i = shortUrl.lastIndexOf('/') + 1;
        return m.get(shortUrl.substring(i));
    }
}

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

class Solution {
public:
    // Encodes a URL to a shortened URL.
    string encode(string longUrl) {
        string v = to_string(++idx);
        m[v] = longUrl;
        return domain + v;
    }

    // Decodes a shortened URL to its original URL.
    string decode(string shortUrl) {
        int i = shortUrl.rfind('/') + 1;
        return m[shortUrl.substr(i, shortUrl.size() - i)];
    }

private:
    unordered_map<string, string> m;
    int idx = 0;
    string domain = "https://tinyurl.com/";
};

// Your Solution object will be instantiated and called as such:
// Solution solution;
// solution.decode(solution.encode(url));

type Codec struct {
    m   map[int]string
    idx int
}

func Constructor() Codec {
    m := map[int]string{}
    return Codec{m, 0}
}

// Encodes a URL to a shortened URL.
func (this *Codec) encode(longUrl string) string {
    this.idx++
    this.m[this.idx] = longUrl
    return "https://tinyurl.com/" + strconv.Itoa(this.idx)
}

// Decodes a shortened URL to its original URL.
func (this *Codec) decode(shortUrl string) string {
    i := strings.LastIndexByte(shortUrl, '/')
    v, _ := strconv.Atoi(shortUrl[i+1:])
    return this.m[v]
}

/**
 * Your Codec object will be instantiated and called as such:
 * obj := Constructor();
 * url := obj.encode(longUrl);
 * ans := obj.decode(url);
 */

535. Encode and Decode TinyURL

Description

Solutions

Solution 1

Comments