tags: - cocubes - mock - timed

Mock 01 — Questions

Original CoCubes-style practice. Do not open [[08_Timed_Mocks/Mock_01_Answers|answers]] until your timer ends.

Rules

Aptitude: 30 questions, 30 minutes.
Technical: 30 questions, 30 minutes.
Pseudocode: 20 questions, 20 minutes.
Coding: 2 problems, 30 minutes.
Use rough paper. Do not pause the timer.

Section A — Aptitude (30 minutes)

Quantitative aptitude

What is 20% of 250?
A. 25
B. 40
C. 50
D. 75
A value rises by 10% and then by 20%. What is the net percentage increase?
A. 30%
B. 32%
C. 28%
D. 22%
An item costs 800 and sells for 920. What is the profit percentage?
A. 12%
B. 15%
C. 18%
D. 20%
A:B = 2:3 and A+B = 75. What is A?
A. 25
B. 30
C. 35
D. 45
The average of five numbers is 12. If one number, 8, is removed, what is the average of the remaining numbers?
A. 11
B. 12
C. 13
D. 15
Ten workers complete a job in 12 days. How many days would fifteen equally efficient workers take?
A. 6
B. 8
C. 10
D. 18
A 150 m train moves at 54 km/h. How many seconds does it take to pass a pole?
A. 8
B. 10
C. 12
D. 15
Find the simple interest on 5,000 at 10% per annum for two years.
A. 500
B. 750
C. 1,000
D. 1,500
A bag has three red and five blue balls. What is the probability of selecting a red ball?
A. 3/5
B. 3/8
C. 5/8
D. 1/3
What is the unit digit of 2 raised to power 27?
A. 2
B. 4
C. 6
D. 8

English

Choose the correct sentence.
A. Either of the plans are acceptable.
B. Either of the plans is acceptable.
C. Either of the plan are acceptable.
D. Either plans is acceptable.
She is interested ___ data science.
A. on
B. at
C. in
D. for
Choose the grammatically correct sentence.
A. The committee have submitted its report.
B. The committee has submitted its report.
C. The committee has submitted their report.
D. The committee have submitted their report.
By the time we arrived, the film ___.
A. starts
B. has started
C. had started
D. was start
Meticulous most nearly means:
A. careless
B. very careful
C. extremely noisy
D. uncertain
Choose the antonym of scarce.
A. rare
B. limited
C. abundant
D. insufficient
Choose the correct usage.
A. She is senior than me.
B. She is senior to me.
C. She is more senior than me.
D. She is senior from me.
He is ___ European citizen.
A. a
B. an
C. the
D. no article
Change to passive voice: "They will complete the work tomorrow."
A. The work will complete tomorrow.
B. The work will be completed tomorrow.
C. The work is completed tomorrow.
D. The work has completed tomorrow.
Read the statement: "Green roofs can lower urban temperature and absorb rainwater. Their installation cost is often higher than a conventional roof." Which statement is supported?
A. Green roofs have no environmental benefit.
B. Green roofs always cost less.
C. Green roofs have environmental benefits but may require higher initial spending.
D. Conventional roofs absorb more rainwater.

Reasoning

Find the next number: 4, 9, 16, 25, __.
A. 30
B. 32
C. 36
D. 49
A person walks 5 km north, then 5 km east, then 5 km south. Where is the person from the start?
A. north
B. south
C. east
D. west
All A are B. No B are C. Which conclusion definitely follows?
A. Some A are C.
B. No A are C.
C. All C are A.
D. Some B are C.
If each letter is shifted one position forward, DOG becomes EPH. What does CAT become?
A. DBU
B. CAU
C. DZT
D. EBU
A is B's sister. C is A's mother. How is C related to B?
A. aunt
B. sister
C. mother
D. grandmother
Five people A, B, C, D and E sit in a row of five seats. A is in the middle. B sits immediately left of A. C sits immediately right of A. D sits at the left end. Who sits at the right end?
A. A
B. B
C. C
D. E
All roses are flowers. Some flowers fade quickly. Which conclusion definitely follows?
A. Some roses fade quickly.
B. No roses fade quickly.
C. All flowers are roses.
D. Neither A nor B definitely follows.
What is the smaller angle between the hands of a clock at 3:30?
A. 60 degrees
B. 75 degrees
C. 90 degrees
D. 105 degrees
P is north of Q. R is east of P. S is south of R. S is in which direction from Q?
A. north
B. south
C. east
D. west
Find the next pair: AZ, BY, CX, __.
A. DV
B. DW
C. DX
D. EW

Section B — Technical (30 minutes)

Which data structure follows FIFO order?
A. Stack
B. Queue
C. Heap
D. Tree
Which traversal of a binary search tree returns keys in sorted order?
A. Preorder
B. Postorder
C. Inorder
D. Level order
What is the average lookup time of a well-designed hash table?
A. O(1)
B. O(log n)
C. O(n)
D. O(n log n)
Which sorting algorithm is especially suitable for a singly linked list?
A. Selection sort
B. Merge sort
C. Heap sort only
D. Binary search
Which algorithm finds a shortest path in an unweighted graph?
A. DFS
B. BFS
C. Dijkstra only
D. Quicksort
Which statement is true?
A. Threads in a process have separate address spaces.
B. Processes always share heap memory.
C. Threads in a process commonly share the process address space.
D. A thread cannot be scheduled.
Which CPU scheduling method uses a fixed time quantum?
A. FCFS
B. Round Robin
C. SJF
D. Priority aging
A requested virtual-memory page is not in RAM. This is:
A. cache hit
B. page fault
C. deadlock
D. fragmentation
Which is not one of the four necessary deadlock conditions?
A. mutual exclusion
B. hold and wait
C. preemption allowed
D. circular wait
Paging divides memory into:
A. variable-sized logical segments only
B. fixed-sized pages and frames
C. one continuous block
D. stack and queue blocks
Which is a primary advantage of a microcontroller in an embedded product?
A. It always needs external RAM and I/O.
B. CPU, memory and I/O can be integrated on one chip.
C. It cannot handle interrupts.
D. It is intended only for desktop operating systems.
Which component converts an analogue sensor voltage into a digital number?
A. DAC
B. ADC
C. PWM
D. GPIO
Which component can recover an unattended controller from a software hang?
A. cache
B. watchdog timer
C. compiler
D. heat sink
Which serial interface is commonly two-wire and addressed?
A. UART
B. SPI
C. I2C
D. HDMI
Which statement best describes UART?
A. It is normally asynchronous serial communication using transmit/receive lines.
B. It is a routing protocol.
C. It converts analogue values to digital values.
D. It is only a storage technology.
Which transport protocol provides ordered, reliable delivery?
A. UDP
B. TCP
C. ARP
D. ICMP
Which protocol has lower overhead but no delivery guarantee?
A. TCP
B. UDP
C. HTTP
D. FTP
IP routing belongs primarily to which OSI layer?
A. Data Link
B. Network
C. Transport
D. Application
What is the conventional default port for DNS?
A. 22
B. 25
C. 53
D. 80
A /27 IPv4 subnet has how many traditional usable host addresses?
A. 14
B. 30
C. 62
D. 126
ARP maps:
A. domain name to IP address
B. IP address to MAC address on local network
C. TCP port to process
D. private IP to public IP
DHCP is used mainly to:
A. encrypt web traffic
B. assign IP configuration automatically
C. resolve domain names
D. route packets between networks
Which HTTP status most directly indicates that credentials are required/invalid?
A. 200
B. 301
C. 401
D. 404
Which development model is most sequential and best when requirements are stable?
A. Agile
B. Waterfall
C. DevOps
D. Kanban only
In Scrum, a short time-boxed development iteration is called:
A. branch
B. sprint
C. build
D. defect
Continuous integration mainly means:
A. writing no tests until release
B. frequently merging changes with automated build/test feedback
C. manually deploying once a year
D. replacing all version control
Testing existing features after a code change is:
A. regression testing
B. retesting only
C. alpha testing only
D. static analysis only
For a valid input range of 1 to 50, which set is a standard boundary-value set?
A. 1, 2, 49, 50
B. 0, 1, 50, 51
C. 10, 20, 30, 40
D. -10, 0, 10, 60
Selenium is best known as a:
A. UI web-test automation tool
B. relational database
C. compiler
D. DNS server
Severity in defect reporting mainly refers to:
A. order in which a developer happens to fix a defect
B. technical/business impact of the defect
C. number of test cases written
D. length of a defect title

Section C — Pseudocode (20 minutes)

What is displayed?

SET s = 0
FOR i = 1 TO 5
  IF i MOD 2 = 0 THEN SET s = s + i
END FOR
DISPLAY s

A. 5
B. 6
C. 9
D. 15
What is displayed?

SET n = 305, r = 0
WHILE n > 0
  SET r = r * 10 + (n MOD 10)
  SET n = n DIV 10
END WHILE
DISPLAY r

A. 305
B. 503
C. 53
D. 8
What is G(4)?

FUNCTION G(n)
  IF n <= 1 THEN RETURN 1
  ELSE RETURN n * G(n - 1)
END FUNCTION

A. 4
B. 10
C. 24
D. 120
What is displayed?

SET a = 3, b = 5
SET a = a + b
SET b = a - b
SET a = a - b
DISPLAY a, b

A. 3, 5
B. 5, 3
C. 8, 3
D. 5, 8
What is displayed?

SET x = 1
WHILE x < 20
  SET x = x * 3
END WHILE
DISPLAY x

A. 9
B. 18
C. 20
D. 27
What is displayed?

SET c = 0
REPEAT
  SET c = c + 2
UNTIL c >= 5
DISPLAY c

A. 4
B. 5
C. 6
D. 8
What is displayed?

SET x = 7, y = 7
IF x > y THEN
  DISPLAY "greater"
ELSE
  IF x = y THEN DISPLAY "equal"
  ELSE DISPLAY "less"
  END IF
END IF

A. greater
B. equal
C. less
D. no output
What is displayed?

SET c = 0
FOR i = 10 TO 16
  IF i MOD 3 = 1 THEN SET c = c + 1
END FOR
DISPLAY c

A. 2
B. 3
C. 4
D. 7
What is the time complexity?

FOR i = 1 TO n
  SET j = 1
  WHILE j <= n
    SET j = j * 2
  END WHILE
END FOR

A. O(1)
B. O(log n)
C. O(n)
D. O(n log n)
What is displayed?

SET p = 2, q = 3
SET r = p
SET p = q
SET q = r
DISPLAY p, q

A. 2, 3
B. 3, 2
C. 3, 3
D. 2, 2
What is displayed?

SET n = 729, sum = 0
WHILE n > 0
  SET sum = sum + (n MOD 10)
  SET n = n DIV 10
END WHILE
DISPLAY sum

A. 9
B. 16
C. 18
D. 27
What is H(5)?

FUNCTION H(n)
  IF n <= 0 THEN RETURN 0
  ELSE RETURN n + H(n - 2)
END FUNCTION

A. 5
B. 6
C. 9
D. 15
An array is explicitly indexed from 1 to 4: A[1]=2, A[2]=4, A[3]=6, A[4]=8. What is displayed?

SET s = 0
FOR i = 1 TO 4
  SET s = s + A[i]
END FOR
DISPLAY s

A. 16
B. 18
C. 20
D. 22
What is displayed?

SET n = 14
CASE n MOD 3 OF
  0: DISPLAY "A"
  1: DISPLAY "B"
  2: DISPLAY "C"
END CASE

A. A
B. B
C. C
D. no output
What is displayed?

SET a = 9, b = 4
IF a DIV b > 2 THEN
  DISPLAY "H"
ELSE
  DISPLAY "L"
END IF

A. H
B. L
C. 2
D. error
What sequence is displayed?

SET f = 0, g = 1
FOR i = 1 TO 3
  DISPLAY f
  SET f = f + g
  SET g = f + g
END FOR

A. 0, 1, 3
B. 0, 1, 1
C. 1, 2, 3
D. 0, 2, 4
How many times does the loop body execute?

SET n = 20, c = 0
WHILE n > 0
  SET n = n DIV 2
  SET c = c + 1
END WHILE

A. 4
B. 5
C. 6
D. 20
What is the time complexity?

SET i = 1
WHILE i <= n
  SET i = i * 2
END WHILE

A. O(1)
B. O(log n)
C. O(n)
D. O(n²)
What is displayed?

SET x = 10
IF NOT (x < 5 OR x > 12) THEN
  DISPLAY "yes"
ELSE
  DISPLAY "no"
END IF

A. yes
B. no
C. 10
D. no output
What happens?

SET n = 1
WHILE n != 0
  SET n = n + 2
END WHILE
DISPLAY n

A. Displays 0
B. Displays 1
C. Infinite loop for normal integers without overflow
D. Displays 3

Section D — Coding (30 minutes)

Coding Problem 1 — Two sum positions

Given an integer array of length n and integer target T, print any two distinct zero-based positions whose values sum to T. If no such pair exists, print -1.

Input:

n
a1 a2 ... an
T

Output:

i j

or:

-1

Example:

Input
5
2 7 11 15 3
10

Output
1 4

Constraints: 2 <= n <= 200000. Values may be negative.

Coding Problem 2 — Longest equal-half digit substring

Given a string S of decimal digits, find the maximum even length L for which S contains a contiguous substring of length L whose first half and second half have equal digit sums. Print L; print 0 if no such substring exists.

Example:

Input
123123

Output
6

Explanation: 123 and 123 have equal digit sums.

Constraints: 1 <= length(S) <= 2000.

When time ends, open [[08_Timed_Mocks/Mock_01_Answers|Mock 01 answers]].