Coding questions
BCG Online Assessment
Overview
Here is how public prep guides and student write-ups describe the BCG online assessment. This is not an official company brochure.
Casey online case is BCG’s distinctive digital gate.
Usual selection rounds
Rounds students usually mention: Application screen → Casey chatbot / online case (+ HR prelim in some guides) → Case interviews → Final partner rounds
| Item | From student reports |
|---|---|
| Platform | Casey chatbot / online case |
| Online test summary | BCG online case assessment before or alongside early interviews; not a coding contest. |
| Eligibility notes | Selective resume screen at target campuses |
| Branches (reported) | MBA/undergrad target schools |
Online test sections
| Section | Questions | Time | Notes |
|---|---|---|---|
| Online case (Casey) | n/a | - | - |
Extra notes from sources
- Check your college placement email for the platform, section order, and timing.
Sample practice question styles
These are practice questions for speed - not claimed to be from a real BCG live paper.
Coding Q1: Move zeros
Problem: Move all zeros in an array to the end while keeping the relative order of non-zero elements.
Approach: Two pointers: write non-zeros toward the front, then fill the remainder with zeros. Or swap zeros as you scan.
Complexity: O(n) time, O(1) space
BCG tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.
Coding Q2: Rotate array
Problem: Rotate an array to the right by k steps. Example: [1,2,3,4,5,6,7], k = 3 → [5,6,7,1,2,3,4].
Approach: Normalize k %= n. Reverse the whole array, reverse the first k elements, then reverse the rest. That yields the rotation in place.
Complexity: O(n) time, O(1) space
BCG tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.
Coding Q3: First unique character
Problem: Find the first non-repeating character in a string and return its index, or -1 if none exists.
Approach: Count frequencies in one pass (hash map or array of 26 for lowercase). Second pass returns the first index with count 1.
Complexity: O(n) time
BCG tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.
Coding Q4: Stack with min
Problem: Design a stack that supports push, pop, top, and getMin in average O(1) time.
Approach: Keep a parallel min-stack (or store pairs). When pushing, also push the new minimum. When popping, pop both stacks.
Complexity: O(1) per operation amortized
BCG tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.
Prep tips from those student reports
- Casey practice
- Case math + structure
- Fit stories
Sources
- Consulting Recruiting in India 2026 - Hacking the Case Interview (other)
- How MBB Recruiting Works - Case Interview Hub (other)
These notes come from public reports and can differ by campus, year, and role. If your college placement email or the official careers/notification PDF says something different, follow that.
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