# 2022-06-29

## [535. Encode and Decode TinyURL](https://leetcode.com/problems/encode-and-decode-tinyurl/)

### Description

> Note: This is a companion problem to the [System Design](https://leetcode.com/discuss/interview-question/system-design/) problem: [Design TinyURL](https://leetcode.com/discuss/interview-question/124658/Design-a-URL-Shortener-\(-TinyURL-\)-System/).

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

```go
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);
 */
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://a.b.cr/dictionary/algorithm/diary/2022/06/2022-06-29.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.