Coding questions
BEL Online Assessment
Overview
Here is how public prep guides and student write-ups describe the BEL online assessment. This is not an official company brochure.
Defence PSU hiring.
Usual selection rounds
Rounds students usually mention: GATE score and/or CBT as per notification → Interview
| Item | From student reports |
|---|---|
| Platform | GATE / BEL CBT per ad |
| Online test summary | BEL Engineer Trainee recruitment frequently references GATE and/or company CBT in public explainers; always open the current BEL PDF for exact pattern. |
| Eligibility notes | As per BEL notification (often GATE-linked for some ET intakes historically) |
| Branches (reported) | As per ad |
Online test sections
Section-level detail not verified in our source set yet - use the placement email / official PDF.
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 BEL live paper.
Coding Q1: 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
BEL 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: 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
BEL 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: Reverse a string in place
Problem: Given a mutable character array representing a string, reverse it in place without allocating another array of the same size.
Approach: Use two pointers at the start and end. Swap characters, then move inward until the pointers meet. Watch empty and single-character inputs.
Complexity: O(n) time, O(1) extra space
BEL 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: Check prime
Problem: Write a function that returns true if n is prime and false otherwise. Handle n < 2 correctly.
Approach: Return false for n < 2. Trial-divide from 2 to floor(sqrt(n)). If any divisor divides n evenly, it is composite; otherwise prime.
Complexity: O(√n) time
BEL 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
- Current BEL notification
- GATE-level core
Sources
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.