String Questions at Agoda: What to Expect

String manipulation is a core skill tested in Agoda’s technical interviews. With 14 out of 46 total questions tagged as String problems, it’s clear they prioritize this domain. Why? Agoda’s platform handles massive volumes of text data daily—user searches, hotel names, descriptions, reviews, and localization for a global audience. Efficiently parsing, validating, transforming, and matching this data is critical for performance and user experience. Your ability to solve string problems demonstrates you can work with real-world, text-heavy systems.

What to Expect — Types of Problems

Agoda’s string questions tend to focus on practical, applied algorithms rather than abstract puzzles. You can expect these categories:

1. String Parsing & Validation: Tasks like checking if a string is a valid IP address, parsing a log line, or validating input formats (e.g., dates, serial numbers). These test your attention to detail and ability to handle edge cases.
2. Pattern Matching & Searching: Implementing or using algorithms to find substrings, such as applying KMP for efficient search or using regex-like pattern matching. This is common for features like search autocomplete or filtering.
3. String Transformation & Encoding: Problems involving compression (e.g., run-length encoding), formatting, or converting between different representations (like URL encoding).
4. Anagrams & Palindromes: Classic problems that test your grasp of frequency counting and two-pointer techniques, often with a twist like finding all anagram groups in a list of words.
5. Interleaving & Merging: Questions about combining strings under certain constraints, which often map to dynamic programming solutions.

How to Prepare — Study Tips with One Code Example

Focus on mastering a few key patterns rather than memorizing solutions. The most critical patterns are:

• Two Pointers: For palindromes, comparing strings, or in-place modifications.
• Sliding Window: For finding substrings with specific properties (longest, shortest, containing certain characters).
• Hash Map for Frequency Counting: The go-to for anagrams and character validation.
• Dynamic Programming: For interleaving, edit distance, and complex matching.

Practice writing clean, correct code under time pressure. Always clarify input constraints and edge cases (empty strings, Unicode, case sensitivity) before starting.

Here is a key pattern—solving an anagram check using frequency counting—demonstrated in three languages:

def is_anagram(s: str, t: str) -> bool:
    if len(s) != len(t):
        return False
    count = [0] * 26  # Assuming lowercase English letters
    for i in range(len(s)):
        count[ord(s[i]) - ord('a')] += 1
        count[ord(t[i]) - ord('a')] -= 1
    return all(c == 0 for c in count)

Recommended Practice Order

Tackle problems in this order to build foundational skills before combining concepts:

1. Start with basic validation and palindrome problems.
2. Move to frequency-based problems like anagrams.
3. Practice sliding window problems for substrings.
4. Tack more complex parsing and encoding challenges.
5. Finally, attempt dynamic programming problems involving strings, like edit distance.

Practice String at Agoda