Coding questions
CDAC Online Assessment
Overview
Here is how public prep guides and student write-ups describe the CDAC online assessment. This is not an official company brochure.
Training exam vs employment hiring are different products.
Usual selection rounds
Rounds students usually mention: C-CAT (for PG Diploma admissions) or post-specific tests/interviews for jobs
| Item | From student reports |
|---|---|
| Platform | C-CAT for diploma admissions; job posts vary |
| Online test summary | Do not confuse CDAC PG Diploma C-CAT exam with CDAC job recruitment. Job openings often use registration + interview/walk-in as advertised. |
| Eligibility notes | As per C-CAT or project post |
| Branches (reported) | Confirm notification |
Online test sections
Section-level detail not verified in our source set yet - use the placement email / official PDF.
Extra notes from sources
- Clarify training vs employment path.
Sample practice question styles
These are practice questions for speed - not claimed to be from a real CDAC live paper.
Coding Q1: Longest substring without repeating characters
Problem: Given a string s, find the length of the longest substring without repeating characters. Example: ‘abcabcbb’ → 3 (‘abc’).
Approach: Sliding window with a map (or last-seen index) of characters. Expand the right pointer; when a duplicate appears inside the window, move the left pointer past the previous occurrence.
Complexity: O(n) time
CDAC 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: Merge overlapping intervals
Problem: Given a list of intervals [start, end], merge all overlapping intervals and return the non-overlapping set that covers the same ranges.
Approach: Sort by start time. Walk once, merging into the last interval in the result when the next start is ≤ current end; otherwise append a new interval.
Complexity: O(n log n) time from the sort
CDAC 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: Top K frequent elements
Problem: Given an integer array and an integer k, return the k most frequent elements. Order among equals can be arbitrary unless the problem says otherwise.
Approach: Count frequencies with a hash map, then use a heap of size k (or bucket sort by frequency) to extract the top k keys.
Complexity: O(n log k) with a heap
CDAC 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: Linked list cycle
Problem: Given the head of a linked list, return true if there is a cycle and false otherwise.
Approach: Floyd’s tortoise and hare: move one pointer one step and another two steps. If they meet, a cycle exists. If the fast pointer hits null, there is no cycle.
Complexity: O(n) time, O(1) space
CDAC 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
- Decide C-CAT vs job vacancy
- Read that specific notification
Sources
- CDAC C-CAT / recruitment portals (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.