CDAC 2025 aptitude
Quantitative, reasoning, and verbal drills with solutions
CDAC Placement Papers 2025
Overview
This page collects CDAC placement papers from 2025 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 2025 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
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CDAC exam pattern 2025
| 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 2025. They are not leaked live papers. Work them timed, then read the solutions only after you have an answer.
Quantitative aptitude (2025)
Q1: 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
Q2: 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
Q3: 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
Q4: Compound ratio
Problem: If two ratios are 3:5 and 5:7, what is the compound ratio?
Solution: Compound ratio = (3/5) × (5/7) = 3/7, written as 3:7.
Answer: 3:7
Q5: SI three years
Problem: Find simple interest on ₹5000 at 8% per annum for 3 years.
Solution: SI = 5000 × 8 × 3 / 100 = ₹1200.
Answer: ₹1200
Q6: Boat upstream
Problem: A boat’s speed in still water is 15 km/h and the stream is 3 km/h. How long to cover 36 km upstream?
Solution: Upstream speed = 15 − 3 = 12 km/h. Time = 36 / 12 = 3 hours.
Answer: 3 hours
Q7: Mixture milk
Problem: A mixture has milk and water in the ratio 4:1. If 5 litres of water are added to 20 litres of mixture, what is the new milk:water ratio?
Solution: In 20 L: milk = 16 L, water = 4 L. After adding 5 L water: milk 16, water 9. Ratio = 16:9.
Answer: 16:9
Q8: CI vs SI hint
Problem: Find compound interest on ₹10,000 at 10% per annum for 2 years, compounded annually.
Solution: Amount = 10000 × (1.1)² = 10000 × 1.21 = ₹12,100. CI = 12100 − 10000 = ₹2100. (SI for same period would be ₹2000; the extra ₹100 is interest on first-year interest.)
Answer: ₹2100
Logical reasoning (2025)
Q1: 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
Q2: Syllogism
Problem: Statements: All engineers are graduates. Some graduates are managers. Conclusion: Some engineers are managers. Does it follow?
Solution: The ‘some graduates’ who are managers need not overlap with the engineers. The conclusion does not follow necessarily.
Answer: Does not follow
Q3: Direction turn
Problem: A person walks 5 km north, then 3 km east, then 5 km south. How far is he from the start, and in which direction?
Solution: North 5 and south 5 cancel. He is 3 km east of the start.
Answer: 3 km east
Q4: Series multiply
Problem: Find the next number: 3, 9, 27, 81, ?
Solution: Each term is multiplied by 3. Next = 81 × 3 = 243.
Answer: 243
Coding practice (2025)
Coding Q1: 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 Q2: 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 Q3: 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 Q4: 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 Q5: 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 Q6: 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.
Coding Q7: Binary tree level order
Problem: Given the root of a binary tree, return the level-order traversal (breadth-first) as a list of levels.
Approach: Use a queue. For each level, drain the current queue size, collect values, and enqueue children for the next level.
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 Q8: Coin change (min coins)
Problem: Given coin denominations and an amount, return the fewest coins needed to make that amount, or -1 if it is impossible.
Approach: Unbounded knapsack DP: let dp[x] be the minimum coins for amount x. For each coin, update dp[c..amount]. Initialize dp[0] = 0 and the rest to a large sentinel.
Complexity: O(amount × coins)
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 2025 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