Is Encode and Decode TinyURL easy or hard?

Encode and Decode TinyURL is rated Medium difficulty on LeetCode. The core implementation is straightforward with a hash map, but interviewers may expect improvements like Base62 encoding, collision handling, or scalable key generation.

Encode and Decode TinyURL Python/Java solution

Typical solutions implement a class with two methods: encode and decode. Python versions often use a dictionary to map IDs to URLs, while Java versions use HashMap. Many implementations convert the numeric ID to a Base62 string to produce shorter URLs.

How to solve Encode and Decode TinyURL in O(1)?

Generate a unique identifier for each new URL and store a mapping between the identifier and the original string in a hash table. The short URL contains this identifier (often encoded in Base62). Encoding inserts the mapping in O(1), and decoding extracts the identifier and performs a constant-time lookup.

What is the best approach for Encode and Decode TinyURL?

The most practical approach uses a hash table that maps a generated short key to the original long URL. Each encode operation generates a unique ID, converts it to a short code (often Base62), and stores the mapping. Both encoding and decoding run in O(1) time with O(n) storage for all saved URLs.

Is Encode and Decode TinyURL asked at Google/Amazon/Meta?

URL shortener design problems appear frequently in interviews at large tech companies including Google, Amazon, and Meta. The question tests understanding of hash tables, string handling, and basic system design concepts like unique ID generation and efficient lookups.

What data structure is used in Encode and Decode TinyURL?

A hash table is the core data structure. It stores the relationship between a short key and the original URL so decoding can retrieve the correct value in constant time. Some implementations also use arrays or counters to generate unique IDs before encoding them.

What is the time complexity of Encode and Decode TinyURL?

Both encode and decode operations run in O(1) time on average when a hash table stores the mapping between short codes and original URLs. Space complexity is O(n) because every encoded URL must be stored to support future decoding.

Description Solution Video 9:02

535. Encode and Decode TinyURL

Medium86.5% acceptance9 companies

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.

Asked at 9 companies

Revolut Shopify Uber Salesforce

Google Amazon Meta Apple Microsoft

Topics

9:02

Still stuck?Read 3 approaches, or watch a walkthrough.

Open solution

LanguageLoading editor…

1class Codec:

  def encode(self, longUrl: str) -> str:
      """Encodes a URL to a shortened URL.
      """
      

  def decode(self, shortUrl: str) -> str:
      """Decodes a shortened URL to its original URL.
      """
      

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

Starter codePython 3Spaces: 4

Examples

Case 1

Input

"https://leetcode.com/problems/design-tinyurl"

Your code is saved on this device.Solution