GATE CSE 2020 Question Paper with Solutions & Answer Key

Engineering Mathematics and Programming and Data Structures together made up 24 of 82 marks, up 11 from GATE CSE 2019. 22 of 53 questions were NAT, the most since 2016. Programming in C was the heaviest single topic with 5 marks across 3 questions. Computer Organization and Architecture moved the most against GATE CSE 2019: up 8 marks.

1. Q1 · MCQ · 1 mark · CalculusConsider the functions I. e-x II. x2 - sin x III. √(x3 + 1) Which of the above functions is/are increasing everywhere in [0,1]?
2. Q2 · MCQ · 1 mark · Asymptotic AnalysisFor parameters a and b, both of which are (1), T(n) = T(n1/a) + 1, and T(b) = 1. Then T(n) is
3. Q3 · MCQ · 1 mark · I/O Interface, Interrupts and DMAConsider the following statements. I. Daisy chaining is used to assign priorities in attending interrupts. II. When a device raises a vectored interrupt, the CPU does po…
4. Q4 · MCQ · 1 mark · ALU DesignConsider the following data path diagram. Consider an instruction: R0 R1 + R2. The following steps are used to execute it over the given data path. Assume that PC is inc…
5. Q5 · MCQ · 1 mark · Binary Search TreesThe preorder traversal of a binary search tree is 15, 10, 12, 11, 20, 18, 16, 19. Which one of the following is the postorder traversal of the tree?
6. Q6 · MCQ · 1 mark · Asymptotic AnalysisWhat is the worst case time complexity of inserting n2 elements into an AVL-tree with n elements initially?
7. Q7 · MCQ · 1 mark · Regular Expressions and Finite AutomataWhich one of the following regular expressions represents the set of all binary strings with an odd number of 1's?
8. Q8 · MCQ · 1 mark · Regular and Context-Free LanguagesConsider the following statements. I. If L1 ∪ L2 is regular, then both L1 and L2 must be regular. II. The class of regular languages is closed under infinite union. Whic…
9. Q9 · MCQ · 1 mark · Runtime EnvironmentsConsider the following statements. I. Symbol table is accessed only during lexical analysis and syntax analysis. II. Compilers for programming languages that support rec…
10. Q10 · MCQ · 1 mark · Context-Free Grammars and PDAsConsider the language L = {an n ≥ 0} ∪ {an bn n ≥ 0} and the following statements. I. L is deterministic context-free. II. L is context-free but not deterministic contex…
11. Q11 · MCQ · 1 mark · Memory Management and Virtual MemoryConsider allocation of memory to a new process. Assume that none of the existing holes in the memory will exactly fit the process’s memory requirement. Hence, a new hole…
12. Q12 · MCQ · 1 mark · Processes, Threads and IPCConsider the following statements about process state transitions for a system using preemptive scheduling. I. A running process can move to ready state. II. A ready pro…
13. Q13 · MCQ · 1 mark · SQLConsider a relational database containing the following schemas. The primary key of each table is indicated by underlining the constituent fields. SELECT s.sno, s.sname…
14. Q14 · MCQ · 1 mark · ER ModelWhich one of the following is used to represent the supporting many-one relationships of a weak entity set in an entity-relationship diagram?
15. Q15 · MCQ · 1 mark · IPv4 FragmentationConsider the following statements about the functionality of an IP based router. I. A router does not modify the IP packets during forwarding. II. It is not necessary fo…
16. Q16 · MCQ · 1 mark · Linear Structures, Trees and HeapsWhat is the worst case time complexity of inserting n elements into an empty linked list, if the linked list needs to be maintained in sorted order?
17. Q17 · NAT · 1 mark · Discrete MathematicsLet R be the set of all binary relations on the set {1,2,3}. Suppose a relation is chosen from R at random. The probability that the chosen relation is reflexive (round…
18. Q18 · NAT · 1 mark · Discrete MathematicsLet G be a group of 35 elements. Then the largest possible size of a subgroup of G other than G itself is …
19. Q19 · NAT · 1 mark · Combinational and Sequential CircuitsA multiplexer is placed between a group of 32 registers and an accumulator to regulate data movement such that at any given point in time the content of only one registe…
20. Q20 · NAT · 1 mark · Combinational and Sequential CircuitsIf there are m input lines and n output lines for a decoder that is used to uniquely address a byte addressable 1 KB RAM, then the minimum value of m + n is …
21. Q22 · NAT · 1 mark · Programming in CConsider the following C program. #include int main() { int a[4][5]={{1, 2, 3, 4, 5}, {6, 7, 8, 9, 10}, {11, 12, 13, 14, 15}, {16, 17, 18 , 19, 20}}; printf("%d ", *(*(a…
22. Q23 · NAT · 1 mark · Searching, Sorting and HashingConsider a double hashing scheme in which the primary hash function is h1(k) = k mod 23, and the secondary hash function is h2(k) = 1 + (k mod 19). Assume that the table…
23. Q24 · NAT · 1 mark · Lexical Analysis, Parsing and SDTConsider the following grammar. S → aSB d B → b The number of reduction steps taken by a bottom-up parser while accepting the string aaadbbb is …
24. Q25 · NAT · 1 mark · DNS and HTTPAssume that you have made a request for a web page through your web browser to a web server. Initially the browser cache is empty. Further, the browser is configured to…
25. Q26 · MCQ · 2 marks · Turing Machines and UndecidabilityWhich of the following languages are undecidable? Note that M indicates encoding of the Turing machine M. L1 = { M L(M) = ∅} L2 = { M, w, q M on input w reaches state q…
26. Q27 · MCQ · 2 marks · Linear AlgebraLet A and B be two n × n matrices over real numbers. Let rank(M) and det(M) denote the rank and determinant of a matrix M, respectively. Consider the following statement…
27. Q28 · MCQ · 2 marks · Boolean Algebra and MinimizationConsider the Boolean function z(a, b, c). Which one of the following minterm lists represents the circuit given above?
28. Q29 · MCQ · 2 marks · Number Representation and ArithmeticConsider three registers R1, R2, and R3 that store numbers in IEEE-754 single precision floating point format. Assume that R1 and R2 contain the values (in hexadecimal n…
29. Q30 · MCQ · 2 marks · Cache Memory and HierarchyA computer system with a word length of 32 bits has a 16 MB byte-addressable main memory and a 64 KB, 4-way set associative cache memory with a block size of 256 bytes.…
30. Q31 · MCQ · 2 marks · Minimum Spanning TreesLet G = (V,E) be a weighted undirected graph and let T be a Minimum Spanning Tree (MST) of G maintained using adjacency lists. Suppose a new weighted edge (u, v) ∈ V × V…
31. Q32 · MCQ · 2 marks · Regular and Context-Free LanguagesConsider the following languages. L1 = {wxyx w, x, y ∈ (0 + 1)+} L2 = {xy x, y ∈ (a + b)*, |x| = |y|, x ≠ y} Which one of the following is TRUE?
32. Q33 · MCQ · 2 marks · Syntax-Directed TranslationConsider the productions A → PQ and A → XY. Each of the five non-terminals A, P, Q, X, and Y has two attributes: s is a synthesized attribute, and i is an inherited attr…
33. Q34 · MCQ · 2 marks · Concurrency and SynchronizationEach of a set of n processes executes the following code using two semaphores a and b initialized to 1 and 0, respectively. Assume that count is a shared variable initia…
34. Q35 · MCQ · 2 marks · CPU and I/O SchedulingConsider the following five disk access requests of the form (request id, cylinder number) that are present in the disk scheduler queue at a given time. (P, 155), (Q, 85…
35. Q36 · MCQ · 2 marks · Integrity Constraints and Normal FormsConsider a relational table R that is in 3NF, but not in BCNF. Which one of the following statements is TRUE?
36. Q37 · MCQ · 2 marks · Transactions and Concurrency ControlConsider a schedule of transactions T1 and T2: Here, RX stands for “Read(X)” and WX stands for “Write(X)”. Which one of the following schedules is conflict equivalent to…
37. Q39 · MCQ · 2 marks · Propositional and First-Order LogicWhich one of the following predicate formulae is NOT logically valid? Note that W is a predicate formula without any free occurrence of x.
38. Q40 · MCQ · 2 marks · Shortest PathsLet G = (V, E) be a directed, weighted graph with weight function w: E → R. For some function f: V → R, for each edge (u, v) ∈ E, define w'(u, v) as w(u, v) + f(u) - f(v…
39. Q41 · MCQ · 2 marks · Binary Search TreesIn a balanced binary search tree with n elements, what is the worst case time complexity of reporting all elements in range [a, b]? Assume that the number of reported el…
40. Q42 · NAT · 2 marks · CombinatoricsThe number of permutations of the characters in LILAC so that no character appears in its original position, if the two L’s are indistinguishable, is …
41. Q43 · NAT · 2 marks · Instruction PipeliningConsider a non-pipelined processor operating at 2.5 GHz. It takes 5 clock cycles to complete an instruction. You are going to make a 5-stage pipeline out of this process…
42. Q44 · NAT · 2 marks · Instruction Set and Addressing ModesA processor has 64 registers and uses 16-bit instruction format. It has two types of instructions: I-type and R-type. Each I-type instruction contains an opcode, a regis…
43. Q45 · NAT · 2 marks · Probability and StatisticsFor n > 2, let a ∈ {0,1}n be a non-zero vector. Suppose that x is chosen uniformly at random from {0,1}n. Then, the probability that Σi=1n ai xi is an odd number is …
44. Q46 · NAT · 2 marks · Programming in CConsider the following C functions. int fun1(int n) { static int i = 0; if (n > 0) { ++i; fun1(n-1); } return(i); } int fun2(int n) { static int i = 0; if (n > 0) { i =…
45. Q47 · NAT · 2 marks · Binary HeapsConsider the array representation of a binary min-heap containing 1023 elements. The minimum number of comparisons required to find the maximum in the heap is …
46. Q48 · NAT · 2 marks · Programming in CConsider the following C functions. int tob(int b, int* arr){ int i; for(i=0; b>0; i++){ if(b%2) arr[i]=1; else arr[i]=0; b = b/2; } return(i); } int pp(int a,int b) { i…
47. Q49 · NAT · 2 marks · Minimum Spanning TreesConsider a graph G = (V, E), where V = {v1, v2, ..., v100}, E = {(vi, vj)|1 ≤ i < j ≤ 100}, and weight of the edge (vi, vj) is |i - j|. The weight of minimum spanning tr…
48. Q50 · NAT · 2 marks · CPU and I/O SchedulingConsider the following set of processes, assumed to have arrived at time 0. Consider the CPU scheduling algorithms Shortest Job First (SJF) and Round Robin (RR). For RR,…
49. Q51 · NAT · 2 marks · Regular Expressions and Finite AutomataConsider the following language. L = {x ∈ {a, b}*| number of a's in x is divisible by 2 but not divisible by 3} The minimum number of states in a DFA that accepts L is …
50. Q52 · NAT · 2 marks · Graph TheoryGraph G is obtained by adding vertex s to K3,4 and making s adjacent to every vertex of K3,4. The minimum number of colours required to edge-colour G is …
51. Q53 · NAT · 2 marks · Memory Management and Virtual MemoryConsider a paging system that uses 1-level page table residing in main memory and a TLB for address translation. Each main memory access takes 100 ns and TLB lookup take…
52. Q54 · NAT · 2 marks · File Organization and IndexingConsider a database implemented using B+ tree for file indexing and installed on a disk drive with block size of 4 KB. The size of search key is 12 bytes and the size of…
53. Q55 · NAT · 2 marks · TCP Flow and Congestion ControlConsider a TCP connection between a client and a server with the following specifications: the round trip time is 6 ms, the size of the receiver advertised window is 50…

How many questions were in GATE CSE 2020?

GATE CSE 2020 had 53 questions for 82 marks: 31 MCQ, 0 MSQ and 22 NAT.

Which subject carried the most marks in GATE CSE 2020?

Engineering Mathematics carried the most marks (13 of 82). The top three were Engineering Mathematics (13), Programming and Data Structures (11), Computer Organization and Architecture (10).

Where can I find the GATE CSE 2020 answer key?

The answer key table on this page lists the answer to every question of GATE CSE 2020. Open any question for its full verified solution.

Is the GATE CSE 2020 paper useful for GATE 2027 preparation?

Yes. Solving past GATE CSE papers shows how marks are spread across subjects and which topics repeat. Compare it with other GATE CSE question papers and the topic-wise GATE CSE PYQs.

• GATE CSE 2019 question paper
• GATE CSE 2021 Set 1 question paper
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• GATE CSE Engineering Mathematics PYQs
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• GATE CSE Computer Organization and Architecture PYQs