GATE CS question library

The $P$ and $V$ operations on counting semaphores, where s is a counting semaphore, are defined as follows: $P(s):$ $s=s-1;$ If $s < 0$ then wait; $V(s):$ $s=s+1;$ If $s \leq0$ then wake up process waiting on s; Assume that $P_b$ and $V_b$ the wait and signal operations on binary semaphores are provided. Two binary semaphores $x_b$ …

The following C function takes a single-linked list of integers as a parameter and rearranges the elements of the list. The function is called with the list containing the integers $1, 2, 3, 4, 5, 6, 7$ in the given order. What will be the contents of the list after function completes execution? struct node { int value; struct node *next; }; void …

Choose the correct option to fill $?1$ and $?2$ so that the program below prints an input string in reverse order. Assume that the input string is terminated by a new line character. void reverse(void) { int c; if(?1) reverse(); ?2 } main() { printf("Enter text"); printf("\n"); reverse(); printf("\n"); }

A computer on a $10\text{Mbps}$ network is regulated by a token bucket. The token bucket is filled at a rate of $2\text{Mbps}$. It is initially filled to capacity with $16\text{Megabits}$. What is the maximum duration for which the computer can transmit at the full $10\text{Mbps}$?

What is printed by the following C program? int f(int x, int *py, int **ppz) { int y, z; **ppz += 1; z = **ppz; // corrected z = *ppz; to z = **ppz; *py += 2; y = *py; x += 3; return x+y+z; } void main() { int c, *b, **a; c = 4; b = &c; a = &b; printf("%d", f(c, b, a)); }

A client process P needs to make a TCP connection to a server process S. Consider the following situation: the server process S executes a $\text{socket()}$, a $\text{bind()}$ and a $\text{listen()}$ system call in that order, following which it is preempted. Subsequently, the client process P executes a $\text{socket()}$ system call followed by …

If a class $B$ network on the Internet has a subnet mask of $255.255.248.0$, what is the maximum number of hosts per subnet?

In the slow start phase of the TCP congestion algorithm, the size of the congestion window:

An LALR(1) parser for a grammar G can have shift-reduce (S-R) conflicts if and only if

Which of the following are true? A programming language which does not permit global variables of any kind and has no nesting of procedures/functions, but permits recursion can be implemented with static storage allocation Multi-level access link (or display) arrangement is needed to arrange activation records only if the programming language being …

Which of the following are regular sets? $\left\{a^nb^{2m} \mid n \geq 0, m \geq 0 \right\}$ $\left\{a^nb^m \mid n =2m \right\}$ $\left\{a^nb^m \mid n \neq m \right\}$ $\left\{xcy \mid x, y, \in \left\{a, b\right\} ^* \right\}$

Match the following NFAs with the regular expressions they correspond to: P Q R S $\epsilon + 0\left(01^*1+00\right)^*01^*$ $\epsilon + 0\left(10^*1+00\right)^*0$ $\epsilon + 0\left(10^*1+10\right)^*1$ $\epsilon + 0\left(10^*1+10\right)^*10^*$

Match the following: …

Which of the following statements is false?

We have a binary heap on $n$ elements and wish to insert $n$ more elements (not necessarily one after another) into this heap. The total time required for this is

You are given the postorder traversal, $P$, of a binary search tree on the $n$ elements $1, 2, \dots, n$. You have to determine the unique binary search tree that has $P$ as its postorder traversal. What is the time complexity of the most efficient algorithm for doing this?

Dijkstra's single source shortest path algorithm when run from vertex $a$ in the above graph, computes the correct shortest path distance to

The subset-sum problem is defined as follows: Given a set $S$ of $n$ positive integers and a positive integer $W$, determine whether there is a subset of $S$ whose elements sum to $W$. An algorithm $Q$ solves this problem in $O(nW)$ time. Which of the following statements is false?

Consider the Quicksort algorithm. Suppose there is a procedure for finding a pivot element which splits the list into two sub-lists each of which contains at least one-fifth of the elements. Let $T(n)$ be the number of comparisons required to sort $n$ elements. Then

A B-tree of order $4$ is built from scratch by $10$ successive insertions. What is the maximum number of node splitting operations that may take place?