What is the optimal time complexity of solving Encode and Decode Strings?

The optimized solution achieves a time complexity of O(n) by using sorting, mathematical shortcuts, or hash table lookups.

What is the auxiliary space complexity for Encode and Decode Strings?

The space complexity is O(n) since we only use a minimal/constant amount of extra memory for tracking variables (or auxiliary space if dynamic structures are allocated).

What are the typical edge cases we must handle in Encode and Decode Strings?

Key edge cases include empty collections, negative or large bounds causing integer overflow, arrays with only one element, or inputs where target criteria are not met.

How can we optimize the brute force approach for Encode and Decode Strings?

Brute force methods often inspect all possible combinations. We optimize this by sorting the input list to enable binary search, or tracking processed items in a set to avoid redundant nested loop lookups.

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Encode and Decode Strings

Learn how to solve the 'Encode and Decode Strings' problem. This detailed resource details brute force and optimized approaches.

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Problem Statement

Easy

Design an algorithm to encode a list of strings to a single string. The encoded string is then decoded back to the original list of strings.

Implement two functions:

- encode(strs: List[str]) -> str — Encodes a list of strings to a single string.

- decode(s: str) -> List[str] — Decodes a single string back to the original list of strings.

The encoded string should be able to handle any possible characters in the input strings, including special characters and empty strings.

Constraints

•0 <= len(strs) <= 200
•0 <= len(strs[i]) <= 200
•strs[i] can contain any possible characters (0-255)

Examples

Example 1

Input

strs = ["hello", "world"]

Output

["hello", "world"]

Explanation

The list is encoded into a single string and then decoded back to the original list ["hello", "world"].

Example 2

Input

strs = [""]

Output

[""]

Explanation

A list containing a single empty string is encoded and decoded correctly.

Example 3

Input

strs = ["we", "say", ":", "yes"]

Output

["we", "say", ":", "yes"]

Explanation

Special characters like ":" are handled correctly during encoding and decoding.

Need a Hint?

Analyze the input constraints. Try sorting first (O(n log n)) or using a hash map/set to track seen elements in O(n) time.

Edge Cases to Watch

Empty list or null input variables
Single item lists/arrays
Extremely large input bounds causing integer or stack overflow

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