Computer Knowledge

Data Structures and Algorithms

1,518 Questions

Data Structures and Algorithms form the core of computer science, focusing on arrays, linked lists, trees, and sorting mechanisms. These concepts are essential for solving complex computational problems efficiently. Test takers preparing for technical and administrative IT exams will find these questions highly relevant.

Array OperationsLinked List ApplicationsSorting AlgorithmsTree Data StructuresMultilevel IndexingAlgorithm Time Complexity

Data Structures and Algorithms Questions

Multiple choice

Given two arrays of numbers a1,..........., an and b1,............, bn where each number is 0 or 1, the fastest algorithm to find the largest span (i, j ) such that ai + ai+1 + .........+ aj = bi + bi + 1 +...........+ bj or report that there is not such span,
  1. Takes O (3n) and $\Omega$(2n) time if hashing is permitted
  2. Takes O (n3) and $\Omega$ (n2.5) time in the key comparison model
  3. Takes $\odot$ (n3) time and space
  4. Takes O ($\sqrt{n}$) time only if the sum of the 2n elements is an even number
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Multiple choice

Consider the following C-function in which a [n] and b [m] are two sorted integer arrays and c [n + m ] be another integer array.

void xyz (int a[ ], int b [ ], int c [ ]) {
  int i, j, k;
  i=j=k=0;
  while ((i < n) && (j < m))
     if (a[i] < b[j]) c[k++] = a[i++];
     else c[k++] = b[j++];
}

Which of the following condition(s) hold(s) after the termination of the while loop?

  1. only (i)

  2. only (ii)

  3. either (i) or (ii) but not both

  4. neither (i) nor (ii)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Multiple choice

A 3-ary max heap is like a binary max heap, but instead of 2 children, nodes have 3 children. A 3-ary heap can be represented by an array as follows: The root is stored in the first location, a[0], nodes in the next level, from left to right, is stored from a[1] to a[3]. The nodes from the second level of the tree from left to right are stored from a[4]location onward. An item x can be inserted into a 3-ary heap containing n items by placing x in the location a[n] and pushing it up the tree to satisfy the heap property.

Which one of the following is a valid sequence of elements in an array representing 3-ary max heap?

  1. 1, 3, 5, 6, 8, 9

  2. 9, 6, 3, 1, 8, 5

  3. 9, 3, 6, 8, 5, 1

  4. 9, 5, 6, 8, 3, 1
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

the all its children

Multiple choice

A 3-ary max heap is like a binary max heap, but instead of 2 children, nodes have 3 children. A 3-ary heap can be represented by an array as follows: The root is stored in the first location, a[0], nodes in the next level, from left to right, is stored from a[1] to a[3]. The nodes from the second level of the tree from left to right are stored from a[4]location onward. An item x can be inserted into a 3-ary heap containing n items by placing x in the location a[n] and pushing it up the tree to satisfy the heap property.

Suppose the elements 7, 2, 10 and 4 are inserted, in that order, into the valid 3- ary max heap found in the above question, Q.76. Which one of the following is the sequence of items in the array representing the resultant heap?

  1. 10, 7, 9, 8, 3, 1, 5, 2, 6, 4

  2. 10, 9, 8, 7, 6, 5, 4, 3, 2, 1

  3. 10, 9, 4, 5, 7, 6, 8, 2, 1, 3

  4. 10, 8, 6, 9, 7, 2, 3, 4, 1, 5
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Multiple choice

An implementation of a queue Q, using two stacks S1 and S2, is given below: void insert (Q, x) { push (S1, x); } void delete (Q) { if (stack-empty(S2)) then if (stack-empty(S1)) then { print(“Q is empty”); return; } else while (!(stack-empty(S1))){ x=pop (S1); push (S2,x); } x=pop (S2); } Let n insert and m ($\le$ n) delete operations be performed in an arbitrary order on an empty queue Q. Let x and y be the number of push and pop operations performed respectively in the process. Which one of the following is true for all m and n?
  1. n + m $\le$ x < 2n and 2m $\le$ y $\le$ n + m
  2. n + m $\le$ x < 2n and 2m $\le$ y $\le$ 2n
  3. 2m $\le$ x < 2n and 2m $\le$ y $\le$ n + m
  4. 2m $\le$ x < 2n and 2m $\le$ y $\le$ 2n
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The order in which insert and delete operations are performed matters here. The best case: Insert and delete operations are performed alternatively. In every delete operation, 2 pop and 1 push operations are performed. So, total m+ n push (n push for insert() and m push for delete()) operations and 2m pop operations are performed. The worst case: First n elements are inserted and then m elements are deleted. In first delete operation, n + 1 pop operations and n push operation are performed. Other than first, in all delete operations, 1 pop operation is performed. So, total m + n pop operations and 2n push operations are performed (n push for insert() and n push for delete())

Multiple choice

Consider a hash table of size seven, with starting index zero, and a hash function (3x + 4) mod 7. Assuming the hash table is initially empty, which of the following is the contents of the table when the sequence 1, 3, 8, 10 is inserted into the table using closed hashing? Note that − denotes an empty location in the table.

  1. 8, −, −, −, −, −, 10

  2. 1, 8, 10, −, −, −, 3

  3. 1, −, −, −, −, −, 3

  4. 1, 10, 8, −, −, −, 3
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation