Binary Search Questions at Samsung: What to Expect

Binary Search isn't just another algorithm at Samsung—it's a core assessment tool. With 8 out of their 69 tagged problems being Binary Search variations, it's clear they prioritize candidates who can efficiently navigate sorted data and apply the "halving" principle to complex scenarios. This focus tests fundamental algorithmic thinking: the ability to optimize beyond brute force, handle edge cases in search spaces, and reduce time complexity from O(n) to O(log n). For roles involving large-scale data processing, embedded systems optimization, or algorithm development, demonstrating mastery here is non-negotiable.

What to Expect — Types of Problems

Samsung's Binary Search problems typically extend beyond textbook array searches. Expect these categories:

1. Classic Search Variations: Finding first/last occurrence, count of an element, or searching in rotated sorted arrays.
2. Answer on a Sorted Range (Binary Search on Answer): The most common and critical pattern. The problem presents a scenario where the answer is an integer within a predictable range (e.g., minimum capacity, maximum minimum distance, or a time threshold). Your task is to binary search over this range of possible answers, using a helper function to check if a candidate value is feasible.
3. Search in Structured Data: Applying the divide-and-conquer logic to matrices, streams, or custom data structures.
4. Integration with Other Concepts: Problems that combine Binary Search with two-pointers, greedy algorithms, or simple math.

The "Binary Search on Answer" pattern is especially prevalent. You won't be searching for an element in an array; instead, you'll be searching for the optimal answer by testing candidate values.

How to Prepare — Study Tips with One Code Example

Master the universal template. A robust Binary Search implementation avoids infinite loops and handles edge cases cleanly. The key is maintaining clear invariants.

Core Tip: Always define what your left and right bounds represent. When writing the condition in your helper function (canSolve(mid)), ask: "If I can achieve mid, can I also achieve a better (larger or smaller) answer?" This determines whether you adjust left or right.

Below is the essential pattern for "Binary Search on Answer," demonstrated in a problem like "Find the minimum capacity required to ship a weight within D days." The canShip function is the critical helper.

def min_capacity(weights, days):
    def can_ship(capacity):
        current_load = 0
        days_needed = 1
        for w in weights:
            if current_load + w > capacity:
                days_needed += 1
                current_load = 0
            current_load += w
        return days_needed <= days

    left, right = max(weights), sum(weights)
    while left < right:
        mid = (left + right) // 2
        if can_ship(mid):
            right = mid  # Try for a smaller capacity
        else:
            left = mid + 1  # Need a larger capacity
    return left

Recommended Practice Order

Build competence sequentially:

1. Fundamentals: Standard search, first/last position.
2. Search Space Transformation: Find min/max of something, peak element, rotated array search.
3. Binary Search on Answer: Start with classic problems (ship capacity, split array largest sum, koko eating bananas). This is the heart of Samsung's questions.
4. Advanced Structures: Search in a 2D matrix or row/column sorted matrix.
5. Samsung-specific Problems: Finally, tackle the 8 tagged problems to familiarize yourself with their presentation and constraints.

Practice Binary Search at Samsung