Array Questions at Tinkoff: What to Expect

Array questions make up nearly half of Tinkoff’s technical interview problem set, with 12 out of 27 total questions focused on this structure. This emphasis is practical: arrays are fundamental to data manipulation, financial data processing, and algorithmic efficiency—core concerns in fintech development. Mastering array problems demonstrates your ability to handle real-world datasets, optimize performance, and implement clean, logical code under time constraints. Success here is often a direct indicator of your readiness for Tinkoff’s technical challenges.

What to Expect — Types of Problems

Tinkoff’s array questions typically fall into a few key categories. You’ll encounter problems requiring in-place manipulation, such as moving zeros, removing duplicates, or rotating arrays without extra space. Sliding window techniques are common for subarray or substring problems involving sums, averages, or contiguous sequences. Two-pointer strategies appear frequently for tasks like pairing elements, reversing sections, or merging sorted arrays. Expect questions that blend these patterns, often with a focus on time and space optimization. Problems may involve multi-dimensional arrays, simulating matrix operations relevant to data analysis. The difficulty ranges from straightforward traversal to complex optimizations where a brute-force approach is insufficient.

How to Prepare — Study Tips with One Code Example

Focus on internalizing patterns rather than memorizing solutions. Start by mastering traversal, then practice each major technique—two-pointer, sliding window, prefix sums—in isolation. Use spaced repetition: solve a problem, revisit it after a day, then a week. Always analyze time and space complexity. For example, the two-pointer technique is essential for in-place operations. Consider removing duplicates from a sorted array in O(n) time and O(1) space:

def removeDuplicates(nums):
    if not nums:
        return 0
    write = 1
    for read in range(1, len(nums)):
        if nums[read] != nums[read - 1]:
            nums[write] = nums[read]
            write += 1
    return write

This pattern uses a read pointer to traverse and a write pointer to build the new array in-place—a frequent Tinkoff expectation.

Recommended Practice Order

Begin with basic traversal and indexing problems to build confidence. Progress to two-pointer problems (like the duplicate removal above), then sliding window challenges. Move on to in-place operations like rotations or partitions. Finally, tackle hybrid problems that combine techniques, such as using a hash map with array traversal for two-sum variants. Always prioritize clarity and efficiency; at Tinkoff, a correct but suboptimal solution may not suffice.

Practice Array at Tinkoff