GATE Computer Science

GATE 2025 Computer Science and Information Technology CS-1 (Forenoon) (English)

GATE Computer Science Previous Year Question Papers — GATE 2025 Computer Science and Information Technology CS-1 (Forenoon) (English). Official GATE Computer Science question-paper PDFs: 2024-2026 from the live organising-institute sites, and 2007-2023 from Internet Archive captures of the IIT Kanpur, IIT Kharagpur, IISc and IIT Guwahati GATE archives that once republished every earlier paper, with the official answer key wherever the same host captured one. Reviewed questions and answers are published for 2024-2025; the remaining years are PDF-only.

Paper details

Year: 2025
Shift: Cs1
Language: English

Validated source link: GATE (rotating organising institute) (retrieved 2026-08-23).

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Question 14

Consider a demand paging memory management system with 32-bit logical address, 20-bit physical address, and page size of 2048 bytes. Assuming that the memory is byte addressable, what is the maximum number of entries in the page table?

2^21
2^20
2^22
2^24

Official answer and source attribution

Answer: 2^21

Official answer: option A. Source: GATE 2025 CS-1, Q.14 (IIT Roorkee final answer key).

Question 18

Let G be any undirected graph with positive edge weights, and T be a minimum spanning tree of G. For any two vertices, u and v, let d1(u, v) and d2(u, v) be the shortest distances between u and v in G and T, respectively. Which ONE of the options is CORRECT for all possible G, T, u and v?

d1(u, v) = d2(u, v)
d1(u, v) ≤d2(u, v)
d1(u, v) ≥d2(u, v)
d1(u, v) ≠d2(u, v)

Official answer and source attribution

Answer: d1(u, v) ≤d2(u, v)

Official answer: option B. Source: GATE 2025 CS-1, Q.18 (IIT Roorkee final answer key).

Question 20

T(n) = 2T(n−1) + n × 2^n for n > 0, T(0) = 1. Which ONE of the following options is CORRECT?

T(n) = Θ(n^2 × 2^n)
T(n) = Θ(n × 2^n)
T(n) = Θ((log n)^2 × 2^n)
T(n) = Θ(4^n)

Official answer and source attribution

Answer: T(n) = Θ(n^2 × 2^n)

Official answer: option A. Source: GATE 2025 CS-1, Q.20 (IIT Roorkee final answer key).

Question 36

Consider a memory system with 1M bytes of main memory and 16K bytes of cache memory. Assume that the processor generates 20-bit memory address, and the cache block size is 16 bytes. If the cache uses direct mapping, how many bits will be required to store all the tag values? [Assume memory is byte addressable, 1K=2^10, 1M=2^20.]

6 × 2^10
8 × 2^10
2^12
2^14

Official answer and source attribution

Answer: 6 × 2^10

Official answer: option A. Source: GATE 2025 CS-1, Q.36 (IIT Roorkee final answer key).

Question 37

A processor has 64 general-purpose registers and 50 distinct instruction types. An instruction is encoded in 32-bits. What is the maximum number of bits that can be used to store the immediate operand for the given instruction? ADD R1, #25 // R1 = R1 + 25

Official answer and source attribution

Answer: 20

Official answer: option B. Source: GATE 2025 CS-1, Q.37 (IIT Roorkee final answer key).

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Question 38

A computer has two processors, M1 and M2. Four processes P1, P2, P3, P4 with CPU bursts of 20, 16, 25, and 10 milliseconds, respectively, arrive at the same time and these are the only processes in the system. The scheduler uses non-preemptive priority scheduling, with priorities decided as follows: • M1 uses priority of execution for the processes as, P1 > P3 > P2 > P4, i.e., P1 and P4 have highest and lowest priorities, respectively. • M2 uses priority of execution for the processes as, P2 > P3 > P4 > P1, i.e., P2 and P1 have highest and lowest priorities, respectively. A process Pi is scheduled to a processor Mk, if the processor is free and no other process Pj is waiting with higher priority. At any given point of time, a process can be allocated to any one of the free processors without violating the execution priority rules. Ignore the context switch time. What will be the average waiting time of the processes in milliseconds?

9.00
8.75
6.50
7.50

Official answer and source attribution

Answer: 9.00

Official answer: option A. Source: GATE 2025 CS-1, Q.38 (IIT Roorkee final answer key).

Question 39

Consider two relations describing teams and players in a sports league: • teams(tid, tname): tid, tname are team-id and team-name, respectively • players(pid, pname, tid): pid, pname, and tid denote player-id, player-name and the team-id of the player, respectively Which ONE of the following tuple relational calculus queries returns the name of the players who play for the team having tname as ′MI′?

{ p. pname | p∈players∧∃t (t∈teams∧p. tid= t. tid∧t. tname= ′MI′)}
{ p. pname | p∈teams∧∃t (t∈players∧p. tid= t. tid∧t. tname= ′MI′)}
{ p. pname | p∈players∧∃t (t∈teams∧t. tname= ′MI′)}
{ p. pname | p∈teams∧∃t (t∈players∧t. tname= ′MI′)}

Official answer and source attribution

Answer: { p. pname | p∈players∧∃t (t∈teams∧p. tid= t. tid∧t. tname= ′MI′)}

Official answer: option A. Source: GATE 2025 CS-1, Q.39 (IIT Roorkee final answer key).

Question 43

Let G(V, E) be an undirected and unweighted graph with 100 vertices. Let d(u, v) denote the number of edges in a shortest path between vertices u and v in V. Let the maximum value of d(u, v), u, v∈V such that u≠v, be 30. Let T be any breadth-first-search tree of G. Which ONE of the given options is CORRECT for every such graph G?

The height of T is exactly 15.
The height of T is exactly 30.
The height of T is at least 15.
The height of T is at least 30.

Official answer and source attribution

Answer: The height of T is at least 15.

Official answer: option C. Source: GATE 2025 CS-1, Q.43 (IIT Roorkee final answer key).