Coding
Practice
Mckinsey Online Assessment
Overview
Section titled “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
Section titled “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 titled “Online test sections”| Section | Questions | Time | Notes |
|---|---|---|---|
| Solve games | n/a | - | Not a coding OA |
Extra notes from sources
Section titled “Extra notes from sources”- Check your college placement email for the platform, section order, and timing.
Sample practice question styles
Section titled “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
Section titled “Prep tips from those student reports”- 50+ live case drills
- PEI stories
- Solve practice
- Target-school placement calendar
Sources
Section titled “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.