String Questions at Zepto: What to Expect

String manipulation is a core skill for software engineers at Zepto. The company's primary product is a 10-minute grocery delivery app, which relies heavily on processing and validating user input, managing item names and descriptions, parsing order data, and handling logistics information like addresses and delivery codes. Efficient string operations directly impact app performance, data integrity, and user experience. With 3 out of 28 total coding questions focused on strings, Zepto clearly prioritizes this fundamental domain.

What to Expect — Types of Problems

Zepto's string problems typically test practical, real-world application over abstract complexity. You can expect questions that mirror the challenges their engineers face daily. Common categories include:

• Validation and Parsing: Checking if user inputs (emails, promo codes, phone numbers) follow specific rules, or extracting meaningful data from formatted strings (like order IDs or address lines).
• Efficient Search and Comparison: Finding substrings, such as matching product names in a search query or identifying duplicate entries in a list of items. Problems may involve pattern matching or anagrams.
• String Transformation: Modifying strings according to business logic, like standardizing formatting, compressing data, or implementing a simple encoder/decoder.
• Two-Pointer and Sliding Window Techniques: These are frequently used for optimizing operations on strings, such as finding the longest substring without repeating characters or checking for palindromes, which are common in interview settings.

The problems are designed to assess your ability to write clean, bug-free code under constraints and your knowledge of language-specific string APIs.

How to Prepare — Study Tips with One Code Example

Focus on mastering fundamental operations and key patterns. Practice writing code by hand or in a simple editor to build fluency. Understand the time and space complexity of your solutions. A critical pattern to internalize is the Two-Pointer Technique, especially for in-place modifications or palindrome checks.

For example, a classic problem is reversing a string in-place. The efficient approach uses two pointers, one at the start and one at the end, swapping characters as they move toward the center.

def reverse_string(s):
    """Reverses a list of characters in-place."""
    left, right = 0, len(s) - 1
    while left < right:
        s[left], s[right] = s[right], s[left]
        left += 1
        right -= 1
# Example: s = ['h','e','l','l','o'] becomes ['o','l','l','e','h']

Recommended Practice Order

1. Start with basic manipulation: reversing, anagrams, and palindrome checks.
2. Move to core algorithms: two-pointer and sliding window patterns.
3. Practice parsing and validation problems using regular expressions (understand them, but don't rely solely on them).
4. Finally, tackle more complex problems that combine these concepts, like substring searches or string compression.

Practice String at Zepto