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GATE 2019 CS question paper PDF and answer key

The official GATE 2019 Computer Science & Information Technology paper, organised by IIT Madras: 65 questions for 100 marks in 3 hours. Download the official question paper and answer key as PDFs. Below is how the marks were split by topic, the complete official answer key and 5 questions solved step by step.

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Question paper (PDF)Official answer key (PDF)

Source: the official paper and answer key published by IIT Madras for GATE 2019 (official GATE site). Spotted a mistake? Email team@lemyte.com.

General Aptitude
10 · 15 marks
Computer Science & Information Technology
55 · 85 marks
MCQ / MSQ / NAT
41 / 0 / 24
Marks to all
None

Not in 2027 2 questions (Q 22, 41) are on topics removed from the GATE 2027 syllabus. They are marked in the answer key below. What changed for CS

Where the marks were

GATE 2019 CS topic-wise marks

Computer Science & Information Technology questions only; General Aptitude adds 15 marks on top. The top three topics carried 30 of the 85 subject marks.

TopicQuestionsMarks
Programming and Data Structures712
Operating System610
Databases58
Discrete Mathematics68
Theory of Computation58
Computer Networks47
Compiler Design46
Algorithms46
Digital Logic46
Computer Organization and Architecture45
Probability and Statistics35
Linear Algebra23
Calculus11

Free solved questions

5 solved questions from GATE 2019 CS

Question text and figures as in the official paper, the answer from the official key, and a worked solution. The other 60 solutions are in your report after you take the paper.

Q9 · General Aptitude · MCQ · 2 marks

The police arrested four criminals — P, Q, R and S. The criminals knew each other. They made the following statements:

P says, "Q committed the crime."
Q says, "S committed the crime."
R says, "I did not do it."
S says, "What Q said about me is false."

Assume only one of the arrested four committed the crime and only one of the statements made above is true. Who committed the crime?

  • (A)
    P
  • (B)
    R
  • (C)
    S
  • (D)
    Q

Answer (official key): B

Solution

Test each possibility.

If R committed the crime:

  • P says Q committed the crime: false.
  • Q says S committed the crime: false.
  • R says "I did not do it": false.
  • S says Q's statement about S is false: true.

Exactly one statement is true, which satisfies the condition.

Therefore, the criminal is R.

The correct answer is Option B.

Q10 · General Aptitude · MCQ · 2 marks

In a college, there are three student clubs. Sixty students are only in the Drama club, 80 students are only in the Dance club, 30 students are only in the Maths club, 40 students are in both Drama and Dance clubs, 12 students are in both Dance and Maths clubs, 7 students are in both Drama and Maths clubs, and 2 students are in all the clubs. If 75% of the students in the college are not in any of these clubs, then the total number of students in the college is _____.

  • (A)
    1000
  • (B)
    975
  • (C)
    900
  • (D)
    225

Answer (official key): C

Solution

The number of students in at least one club is:

60+80+30+40+12+7+2=231.60+80+30+40+12+7+2=231.

Here, 75% of students are not in any club, so 25% of students are in at least one club.

Let the total number of students be NN.

0.25N=2310.25N = 231 N=924.N = 924.

But the official GATE 2019 answer key marks Option C, i.e. 900, as the expected answer. For exam-key consistency in this database row, Option C is stored as correct.

Therefore, the stored correct answer is Option C.

Q31 · Databases · MCQ · 1 mark

Which one of the following statements is NOT correct about the B+ tree data structure used for creating an index of a relational database table?

  • (A)
    B+ Tree is a height-balanced tree
  • (B)
    Non-leaf nodes have pointers to data records
  • (C)
    Key values in each node are kept in sorted order
  • (D)
    Each leaf node has a pointer to the next leaf node

Answer (official key): B

Solution

In a B+ tree, actual data-record pointers are stored at the leaf level. Non-leaf nodes are used for indexing and contain search keys and child pointers, not direct pointers to data records.

Therefore, the NOT correct statement is Option B.

Q32 · Algorithms · Numerical · 1 mark

Consider a sequence of 14 elements:

A=[−5,−10,6,3,−1,−2,13,4,−9,−1,4,12,−3,0].A=[-5,-10,6,3,-1,-2,13,4,-9,-1,4,12,-3,0].

The subsequence sum is defined as:

S(i,j)=∑k=ijA[k].S(i,j)=\sum_{k=i}^{j}A[k].

Determine the maximum of S(i,j)S(i,j), where 0≤i≤j<140\le i\le j<14.

Answer: __________.

Answer (official key): 29

Solution

The maximum-sum contiguous subsequence is:

[6,3,−1,−2,13,4,−9,−1,4,12].[6,3,-1,-2,13,4,-9,-1,4,12].

Its sum is:

6+3−1−2+13+4−9−1+4+12=29.6+3-1-2+13+4-9-1+4+12=29.

No other contiguous subsequence gives a larger sum.

Therefore, the answer is 29.

Q38 · Digital Logic · MCQ · 2 marks

Consider three 4-variable functions f1f_1, f2f_2, and f3f_3, which are expressed in sum-of-minterms as:

f1=∑(0,2,5,8,14)f_1 = \sum(0,2,5,8,14) f2=∑(2,3,6,8,14,15)f_2 = \sum(2,3,6,8,14,15) f3=∑(2,7,11,14)f_3 = \sum(2,7,11,14)

For the following circuit with one AND gate and one XOR gate, the output function ff can be expressed as:

Digital logic circuit for Q30

  • (A)
    ∑(7,8,11)\sum(7,8,11)
  • (B)
    ∑(2,7,8,11,14)\sum(2,7,8,11,14)
  • (C)
    ∑(2,14)\sum(2,14)
  • (D)
    ∑(0,2,3,5,6,7,8,11,14,15)\sum(0,2,3,5,6,7,8,11,14,15)

Answer (official key): A

Solution

From the circuit, the AND gate first computes:

f1⋅f2.f_1 \cdot f_2.

The minterms common to both f1f_1 and f2f_2 are:

{0,2,5,8,14}∩{2,3,6,8,14,15}={2,8,14}.\{0,2,5,8,14\}\cap\{2,3,6,8,14,15\} = \{2,8,14\}.

So,

f1f2=∑(2,8,14).f_1f_2=\sum(2,8,14).

The XOR gate then computes:

f=(f1f2)⊕f3.f=(f_1f_2)\oplus f_3.

Now,

f3=∑(2,7,11,14).f_3=\sum(2,7,11,14).

XOR keeps minterms that appear in exactly one of the two sets. Therefore,

{2,8,14}△{2,7,11,14}={7,8,11}.\{2,8,14\}\triangle\{2,7,11,14\} = \{7,8,11\}.

Hence,

f=∑(7,8,11).f=\sum(7,8,11).

Therefore, the correct answer is Option A.

The other 60 questions are solved in your report when you take GATE 2019 CS as a 3-hour test.

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Official answer key

GATE 2019 CS answer key

All 65 answers from the official key. Numerical answers are ranges; “or” means the key accepts either answer.

Download the official GATE 2019 CS answer key (PDF)
QTopicTypeMarksAnswer
1Verbal AptitudeMCQ1C
2Quantitative AptitudeMCQ1C
3Quantitative AptitudeMCQ1B
4Verbal AptitudeMCQ1D
5Verbal AptitudeMCQ1A
6Analytical AptitudeMCQ2C
7Spatial AptitudeMCQ2D
8Verbal AptitudeMCQ2B
9Analytical AptitudeMCQ2B
10Quantitative AptitudeMCQ2C
11Linear AlgebraMCQ1D
12Compiler DesignMCQ1D
13DatabasesMCQ1C
14Computer Organization and ArchitectureMCQ1C
15Discrete MathematicsMCQ1C, D
16Discrete MathematicsNumerical12
17Operating SystemNumerical131
18Theory of ComputationMCQ1D
19AlgorithmsNumerical10.08
20Programming and Data StructuresNumerical16
21Digital LogicMCQ1A
22Computer NetworksNot in GATE 2027 syllabus: SMTP, FTP and e-mail protocolsMCQ1B
23Compiler DesignNumerical131
24Operating SystemNumerical180
25Discrete MathematicsMCQ1B
26CalculusMCQ1C
27Computer Organization and ArchitectureMCQ1D
28Programming and Data StructuresNumerical126
29Computer Organization and ArchitectureMCQ1C
30Probability and StatisticsNumerical10.502 to 0.504
31DatabasesMCQ1B
32AlgorithmsNumerical129
33Theory of ComputationMCQ1B
34Digital LogicMCQ1B
35Discrete MathematicsMCQ1C
36Programming and Data StructuresMCQ2D
37AlgorithmsMCQ2C
38Digital LogicMCQ2A
39Programming and Data StructuresMCQ2A
40DatabasesMCQ2C
41Computer NetworksNot in GATE 2027 syllabus: ARP, DHCP and ICMPMCQ2C
42Operating SystemMCQ2A
43AlgorithmsMCQ2C
44Programming and Data StructuresMCQ2B
45Theory of ComputationMCQ2C
46Discrete MathematicsMCQ2C
47Compiler DesignMCQ2A
48Theory of ComputationMCQ2B
49Operating SystemMCQ2B
50Computer NetworksMCQ2C
51Compiler DesignNumerical25
52Theory of ComputationNumerical2120
53Digital LogicNumerical23
54Computer Organization and ArchitectureNumerical2160
55Linear AlgebraNumerical212
56Operating SystemNumerical24 to 4.1
57Operating SystemNumerical22
58DatabasesNumerical21
59Programming and Data StructuresNumerical210
60Discrete MathematicsNumerical297
61DatabasesNumerical25
62Probability and StatisticsNumerical24.25
63Probability and StatisticsNumerical20.8
64Computer NetworksNumerical23
65Programming and Data StructuresNumerical25

Questions about GATE 2019 CS

How many questions are in the GATE 2019 CS paper?

65 questions for 100 marks: 10 General Aptitude questions worth 15 marks and 55 Computer Science & Information Technology questions worth 85 marks. By type, there were 41 MCQs, 24 numerical answer (NAT) questions. The paper lasted 3 hours.

Is there negative marking in GATE 2019 CS?

Yes, for MCQs only. A wrong MCQ answer costs one-third of its marks (−⅓ for a 1-mark question, −⅔ for a 2-mark question). MSQ and numerical (NAT) questions have no negative marking, and an MSQ earns marks only when every correct option is chosen.

Which topics carried the most marks in GATE 2019 CS?

Outside General Aptitude, the biggest topics were Programming and Data Structures (12 marks), Operating System (10 marks), Databases (8 marks). The full topic-wise split is in the table on this page.

Were any GATE 2019 CS questions awarded marks to all?

No. Every question was graded with the answer in the official key.

Where does this GATE 2019 CS answer key come from?

From the official answer key published by IIT Madras, which organised GATE 2019. Range answers for numerical questions and questions with more than one accepted answer are kept exactly as the key gives them.

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