Coding questions
Mckinsey Online Assessment
Overview
Here is how public prep guides and student write-ups describe the McKinsey online assessment. This is not an official company brochure.
Case + Solve - not aptitude/coding service OA.
Usual selection rounds
Rounds students usually mention: Application / resume screen → McKinsey Solve (problem-solving game) → Case + PEI/fit interviews → Partner final round
| Item | From student reports |
|---|---|
| Platform | McKinsey Solve digital assessment |
| Online test summary | Psychometric mini-games (ecosystem + tower-defense style cited in guides) before interview rounds; cuts a large share of shortlisted applicants. |
| Eligibility notes | Highly selective resume screen (top academics + leadership proof) |
| Branches (reported) | Primarily IIM/ISB/IIT and select campuses for BA/Associate tracks |
Online test sections
| Section | Questions | Time | Notes |
|---|---|---|---|
| Solve games | n/a | - | Not a coding OA |
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 McKinsey live paper.
Coding Q1: 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
McKinsey 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: 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
McKinsey 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: 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
McKinsey 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: Maximum subarray sum (Kadane)
Problem: Given an integer array, find the contiguous subarray with the largest sum and return that sum. Example: [-2,1,-3,4,-1,2,1,-5,4] → 6 (from [4,-1,2,1]).
Approach: Keep a running sum. If the running sum drops below 0, reset it to 0 before taking the next element (or track the best ending-here value). Track the global maximum as you scan once from left to right.
Complexity: O(n) time, O(1) extra space
McKinsey 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
- 50+ live case drills
- PEI stories
- Solve practice
- Target-school placement calendar
Sources
- Consulting Recruiting in India 2026 - Hacking the Case Interview (other)
- McKinsey India Recruiting - Hacking the Case Interview (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.