CDAC 2024 aptitude
Quantitative, reasoning, and verbal drills with solutions
CDAC Placement Papers 2024
Overview
This page collects CDAC placement papers from 2024 with practice questions, worked solutions, and the exam pattern students reported that cycle. Use it when you want drive history: what the first round looked like, which topics repeated, and how to approach solutions. Work the sets below under a timer, then compare with newer material so your prep matches both established CDAC patterns and recent shifts.
Download / jump links
CDAC 2024 coding
DSA practice aligned to CDAC online assessments
CDAC interview experience
Round structure and tips from student reports
CDAC prep guide
Study plan and weekly schedule
CDAC Aptitude Mock Quiz
Timed placement-style MCQs with score and explanations after you submit. Use it to check speed and accuracy before the real test.
Questions15
Time10 min
Quantitative
Successive discounts of 20% and 10% are equivalent to a single discount of:
Effective = 100 − 80×90/100 = 28%.
Reasoning
Find the next number: 2, 6, 12, 20, 30, ?
Differences +4, +6, +8, +10, +12 → next is 42.
Quantitative
Six people A, B, C, D, E, F are sitting around a circular table. A is opposite to D. B is between A and C. E is not adjacent to A. Who is sitting opposite to E?
In circular arrangement with 6 people, opposite pairs are: (A,D), (B,E), (C,F) Since A is opposite D, and B is between A and C, and E is not adjacent to A E must be opposite B
Quantitative
The ratio of two numbers is 3:4. If their sum is 84, find the numbers.
Let the numbers be 3x and 4x Sum = 3x + 4x = 7x = 84 x = 12 Numbers = 3(12) = 36 and 4(12) = 48
Reasoning
Find the next number: 2, 5, 11, 23, 47, ?
Pattern: Each number = previous × 2 + 1 2×2+1=5, 5×2+1=11, 11×2+1=23, 23×2+1=47 Next: 47×2+1 = 95
Reasoning
Two trains of lengths 120m and 180m are running in opposite directions at speeds of 40 km/hr and 50 km/hr respectively. Find the time taken to cross each other.
Relative speed = 40 + 50 = 90 km/hr = 90 × 5/18 = 25 m/s Total distance = 120 + 180 = 300m Time = 300/25 = 12 seconds
Verbal
"Break the ice" means:
It means to initiate conversation in a social setting.
Quantitative
A cube, painted yellow on all faces is cut into 27 small cubes of equal size. How many small cubes are painted on one face only?
Correct answer: 6
Quantitative
Find the compound interest on ₹5000 for 2 years at 10% per annum, compounded annually.
Correct answer: ₹1050
Quantitative
A person travels first half of distance at 40 km/hr and second half at 60 km/hr. Find average speed.
Let total distance = 2D Time for first half = D/40 Time for second half = D/60 Total time = D/40 + D/60 = D(3+2)/120 = 5D/120 = D/24 Average speed = 2D / (D/24) = 48 km/hr
Verbal
Choose the correct synonym for "Ephemeral":
"Ephemeral" means lasting for a very short time, temporary. "Temporary" is the synonym.
Verbal
Antonym of "Temporary":
Temporary ↔ permanent.
Reasoning
In a row of 30 students, A is 10th from the left. Rank from the right is:
From right = 30-10+1 = 21.
Verbal
One who loves books is a:
Bibliophile = lover of books.
Reasoning
Arrange the words: 1. Elephant 2. Cat 3. Dog 4. Ant
Correct answer: 4, 2, 3, 1
Your score
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CDAC exam pattern 2024
| Section | What shows up | Prep focus |
|---|---|---|
| Technical / domain | Syllabus aligned to the notification | Topic checklist |
| Aptitude | Quant + reasoning | Speed with accuracy |
| Interview | Subject depth + projects | Clear fundamentals |
First round: CDAC Entrance / Recruitment Test
Skills emphasized: C/C++, OS, networks, aptitude
Languages: C, C++, Java, Python
Sample CDAC questions with solutions
These are practice-style questions aligned to patterns students report for CDAC drives around 2024. They are not leaked live papers. Work them timed, then read the solutions only after you have an answer.
Quantitative aptitude (2024)
Q1: Series n(n+1)
Problem: Find the next term: 2, 6, 12, 20, 30, ?
Solution: Pattern: 1×2, 2×3, 3×4, 4×5, 5×6, 6×7. Next = 6 × 7 = 42.
Answer: 42
Q2: Deck probability
Problem: What is the probability of drawing an ace from a standard 52-card deck?
Solution: There are 4 aces in 52 cards. Probability = 4/52 = 1/13.
Answer: 1/13
Q3: Net percent change
Problem: A number is increased by 20% and then decreased by 20%. What is the net percentage change?
Solution: Start with 100 → 120 → 96. Net change = 4% decrease. Formula: successive +a then −a gives −(a²/100)% = −4%.
Answer: 4% decrease
Q4: Consumption cut
Problem: If the price of an item rises by 25%, by what percent should consumption fall so that expenditure stays the same?
Solution: Required reduction = r/(100+r) × 100 with r = 25. = 25/125 × 100 = 20%.
Answer: 20%
Q5: Compound mark-discount
Problem: An article is marked 40% above cost and sold after a 10% discount. Find the profit percent.
Solution: SP = CP × 1.4 × 0.9 = 1.26 CP. Profit = 26%.
Answer: 26%
Q6: Loss to profit shift
Problem: An article sold at 10% loss would give 5% profit if sold for ₹60 more. Find the cost price.
Solution: 0.9P + 60 = 1.05P 60 = 0.15P P = 60 / 0.15 = ₹400.
Answer: ₹400
Q7: Worker scaling
Problem: Eight workers finish a job in 10 days. How many days will 10 workers take for the same job (same pace)?
Solution: Total man-days = 8 × 10 = 80. Days for 10 workers = 80 / 10 = 8 days.
Answer: 8 days
Q8: Distance from speed
Problem: A vehicle travels at 60 km/h for 2.5 hours. How far does it go?
Solution: Distance = speed × time = 60 × 2.5 = 150 km.
Answer: 150 km
Logical reasoning (2024)
Q1: Analogy
Problem: Book is to Reading as Fork is to ?
Solution: A book is used for reading; a fork is used for eating.
Answer: Eating
Q2: Odd one out
Problem: Find the odd one out: 3, 5, 7, 9, 11
Solution: 3, 5, 7, and 11 are prime. 9 = 3×3 is composite, so it is the odd one out.
Answer: 9
Q3: Coding letter shift
Problem: If CAT is coded as DBU, how is DOG coded in the same way?
Solution: Each letter moves +1 in the alphabet: C→D, A→B, T→U. D→E, O→P, G→H → EPH.
Answer: EPH
Q4: Blood relation
Problem: Pointing to a photograph, Ravi says, ‘She is the daughter of my mother’s only son.’ How is the girl related to Ravi?
Solution: Ravi’s mother’s only son is Ravi himself (assuming one son). The girl is therefore Ravi’s daughter.
Answer: Daughter
Coding practice (2024)
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
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: 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
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: 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
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: 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
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 Q5: Valid parentheses
Problem: Given a string containing only ‘()[]’, decide whether the brackets are balanced and correctly nested.
Approach: Scan left to right with a stack. Push opening brackets. On a closing bracket, the stack top must be the matching opener. At the end the stack must be empty.
Complexity: O(n) time, O(n) 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.
Coding Q6: Two Sum
Problem: Given an array of integers and a target, return indices of two numbers that add up to the target. Assume exactly one solution and you may not use the same element twice.
Approach: Walk the array once. For each value x, check whether target − x was seen earlier in a hash map of value → index. If yes, return both indices; else store x.
Complexity: O(n) time, O(n) 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.
Coding Q7: 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 Q8: 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.
Deep prep notes for CDAC
How the CDAC entrance / recruitment test usually feels
Students usually say the first round is time-tight - easy marks vanish if you sit too long on one hard question. For CDAC, skim the paper in a couple of minutes, mark what you can finish cleanly, and protect accuracy. Languages people commonly use: C, C++, Java, Python.
Topic weight hints
| Area | Why it matters at CDAC |
|---|---|
| C/C++ | What usually helps you clear the first round |
| Core CS (OOPs / DBMS / OS) | Technical interview depth |
| Advanced Computing R&D awareness | Helps in managerial / HR conversations |
| Communication | Explain your approach clearly; keep a few real examples ready for HR |
14-Day sprint
- Days 1-3: Learn the 2024 pattern and take two sectional mocks
- Days 4-7: Closed practice on weak topics from your error log
- Days 8-10: Full mocks every other day; review the same day
- Days 11-14: Practice explaining projects out loud, light revision, sleep and IDs ready