2022-06-29

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 deconding it.

Constraints:

• 1 <= url.length <= 10^4

• url is guranteed to be a valid URL.

Solution

Approach #0

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


func Constructor() Codec {
    return Codec{m:make(map[string]string)}
}

// Encodes a URL to a shortened URL.
func (this *Codec) encode(longUrl string) (tiny string) {
	this.id++
    tiny=strconv.Itoa(this.id)
    this.m[tiny]=longUrl
    return
}

// Decodes a shortened URL to its original URL.
func (this *Codec) decode(shortUrl string) string {
    return this.m[shortUrl]
}


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