Data Structure Multiple Choice Questions and Answers on Single Linked List Operations
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1. A linear collection of data elements where the linear node is given by means of pointer is called?
a) Linked list
b) Node list
c) Primitive list
d) None of the mentioned
Answer: a
2. Consider an implementation of unsorted singly linked list. Suppose it has its representation with a head pointer only.
Given the representation, which of the following operation can be implemented in O(1) time?
i) Insertion at the front of the linked list
ii) Insertion at the end of the linked list
iii) Deletion of the front node of the linked list
iv) Deletion of the last node of the linked list
Given the representation, which of the following operation can be implemented in O(1) time?
i) Insertion at the front of the linked list
ii) Insertion at the end of the linked list
iii) Deletion of the front node of the linked list
iv) Deletion of the last node of the linked list
a) I and II
b) I and III
c) I, II and III
d) I, II and IV
Answer: b
3. In linked list each node contain minimum of two fields. One field is data field to store the data second field is?
a) Pointer to character
b) Pointer to integer
c) Pointer to node
d) Node
Answer: c
4. What would be the asymptotic time complexity to add a node at the end of singly linked list, if the pointer is initially pointing to the head of the list?
a) O(1)
b) O(n)
c) θ(n)
d) θ(1)
Answer: c
5. What would be the asymptotic time complexity to add an element in the linked list?
a) O(1)
b) O(n)
c) O(n2)
d) None of the mentioned
Answer: b
6. What would be the asymptotic time complexity to find an element in the linked list?
a) O(1)
b) O(n)
c) O(n2)
d) None of the mentioned
Answer: b
7. What would be the asymptotic time complexity to insert an element at the second position in the linked list?
a) O(1)
b) O(n)
c) O(n2)
d) None of the mentioned
Answer: a
8. The concatenation of two list can performed in O(1) time. Which of the following variation of linked list can be used?
a) Singly linked list
b) Doubly linked list
c) Circular doubly linked list
d) Array implementation of list
Answer: c
9. Consider the following definition in c programming language
struct node { int data; struct node * next; } typedef struct node NODE; NODE *ptr;
Which of the following c code is used to create new node?
a) ptr = (NODE*)malloc(sizeof(NODE));
b) ptr = (NODE*)malloc(NODE);
c) ptr = (NODE*)malloc(sizeof(NODE*));
d) ptr = (NODE)malloc(sizeof(NODE));
Answer: a
Explanation: As it represents the right way to create a node.
10. What kind of linked list is best to answer question like “What is the item at position n?”
a) Singly linked list
b) Doubly linked list
c) Circular linked list
d) Array implementation of linked list
Answer: d
11. Linked lists are not suitable to for the implementation of?
a) Insertion sort
b) Radix sort
c) Polynomial manipulation
d) Binary search
Answer: d
Explanation: It cannot be implemented using linked lists.
12. Linked list is considered as an example of ___________ type of memory allocation.
a) Dynamic
b) Static
c) Compile time
d) None of the mentioned
Answer: a
Explanation: As memory is allocated at the run time.
13. In Linked List implementation, a node carries information regarding
a) Data
b) Link
c) Data and Link
d) None of the mentioned
Answer: b
14. Linked list data structure offers considerable saving in
a) Computational Time
b) Space Utilization
c) Space Utilization and Computational Time
d) None of the mentioned
Answer: c
Explanation: Linked lists saves both space and time.
15. Which of the following points is/are true about Linked List data structure when it is compared with array
a) Arrays have better cache locality that can make them better in terms of performance
b) It is easy to insert and delete elements in Linked List
c) Random access is not allowed in a typical implementation of Linked Lists
d) All of the mentioned
Answer: d
16. What does the following function do for a given Linked List with first node as head?
void fun1(struct node* head) { if(head == NULL) return; fun1(head->next); printf("%d ", head->data); }
a) Prints all nodes of linked lists
b) Prints all nodes of linked list in reverse order
c) Prints alternate nodes of Linked List
d) Prints alternate nodes in reverse order
b) Prints all nodes of linked list in reverse order
c) Prints alternate nodes of Linked List
d) Prints alternate nodes in reverse order
Answer: b
Explanation: fun1() prints the given Linked List in reverse manner.
For Linked List 1->2->3->4->5, fun1() prints 5->4->3->2->1.
17. Which of the following sorting algorithms can be used to sort a random linked list with minimum time complexity?
a) Insertion Sort
b) Quick Sort
c) Heap Sort
d) Merge Sort
Answer: d
Explanation: Both Merge sort and Insertion sort can be used for linked lists. The slow random-access performance of a linked list makes other algorithms (such as quicksort) perform poorly, and others (such as heapsort) completely impossible. Since worst case time complexity of Merge Sort is O(nLogn) and Insertion sort is O(n2), merge sort is preferred.
18. The following function reverse() is supposed to reverse a singly linked list. There is one line missing at the end of the function.
/* Link list node */ struct node { int data; struct node* next; }; /* head_ref is a double pointer which points to head (or start) pointer of linked list */ static void reverse(struct node** head_ref) { struct node* prev = NULL; struct node* current = *head_ref; struct node* next; while (current != NULL) { next = current->next; current->next = prev; prev = current; current = next; } /*ADD A STATEMENT HERE*/ }
What should be added in place of “/*ADD A STATEMENT HERE*/”, so that the function correctly reverses a linked list.
a) *head_ref = prev;
b) *head_ref = current;
c) *head_ref = next;
d) *head_ref = NULL;
a) *head_ref = prev;
b) *head_ref = current;
c) *head_ref = next;
d) *head_ref = NULL;
Answer: a
Explanation: *head_ref = prev; At the end of while loop, the prev pointer points to the last node of original linked list.
We need to change *head_ref so that the head pointer now starts pointing to the last node.
19. What is the output of following function for start pointing to first node of following linked list?
1->2->3->4->5->6 void fun(struct node* start) { if(start == NULL) return; printf("%d ", start->data); if(start->next != NULL ) fun(start->next->next); printf("%d ", start->data); }
a) 1 4 6 6 4 1
b) 1 3 5 1 3 5
c) 1 2 3 5
d) 1 3 5 5 3 1
b) 1 3 5 1 3 5
c) 1 2 3 5
d) 1 3 5 5 3 1
Answer: d
Explanation: fun() prints alternate nodes of the given Linked List, first from head to end, and then from end to head.
If Linked List has even number of nodes, then skips the last node.
20. The following C function takes a simply-linked list as input argument.
It modifies the list by moving the last element to the front of the list and returns
the modified list. Some part of the code is left blank. Choose the correct alternative
to replace the blank line.
It modifies the list by moving the last element to the front of the list and returns
the modified list. Some part of the code is left blank. Choose the correct alternative
to replace the blank line.
typedef struct node { int value; struct node *next; }Node; Node *move_to_front(Node *head) { Node *p, *q; if ((head == NULL: || (head->next == NULL)) return head; q = NULL; p = head; while (p-> next !=NULL) { q = p; p = p->next; } _______________________________ return head; }
a) q = NULL; p->next = head; head = p;
b) q->next = NULL; head = p; p->next = head;
c) head = p; p->next = q; q->next = NULL;
d) q->next = NULL; p->next = head; head = p;
b) q->next = NULL; head = p; p->next = head;
c) head = p; p->next = q; q->next = NULL;
d) q->next = NULL; p->next = head; head = p;
Answer: d
21. 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 the function completes execution?
struct node { int value; struct node *next; }; void rearrange(struct node *list) { struct node *p, * q; int temp; if ((!list) || !list->next) return; p = list; q = list->next; while(q) { temp = p->value; p->value = q->value; q->value = temp; p = q->next; q = p?p->next:0; } }
a) 1, 2, 3, 4, 5, 6, 7
b) 2, 1, 4, 3, 6, 5, 7
c) 1, 3, 2, 5, 4, 7, 6
d) 2, 3, 4, 5, 6, 7, 1
b) 2, 1, 4, 3, 6, 5, 7
c) 1, 3, 2, 5, 4, 7, 6
d) 2, 3, 4, 5, 6, 7, 1
Answer: b
Explanation: The function rearrange() exchanges data of every node with its next node. It starts exchanging data from the first node itself.
22. In the worst case, the number of comparisons needed to search a singly linked list of length n for a given element is
a) log 2 n
b) n⁄2
c) log 2 n – 1
d) n
Answer: d
Explanation: In the worst case, the element to be searched has to be compared with all elements of linked list.
23. Given pointer to a node X in a singly linked list. Only one pointer is given, pointer to head node is not given, can we delete the node X from given linked list?
a) Possible if X is not last node
b) Possible if size of linked list is even
c) Possible if size of linked list is odd
d) Possible if X is not first node
Answer: a
Explanation:
Following are simple steps.
struct node *temp = X->next; X->data = temp->data; X->next = temp->next; free(temp);
24. You are given pointers to first and last nodes of a singly linked list, which of the following operations are dependent on the length of the linked list?
a) Delete the first element
b) Insert a new element as a first element
c) Delete the last element of the list
d) Add a new element at the end of the list
Answer: c
Explanation: a) Can be done in O(1) time by deleting memory and changing the first pointer.
b) Can be done in O(1) time, see push() here
c) Delete the last element requires pointer to previous of last, which can only be obtained by traversing the list.
d) Can be done in O(1) by changing next of last and then last.
25. In the worst case, the number of comparisons needed to search a singly linked list of length n for a given element is
a) log2 n
b) n⁄2
c) log2 n – 1
d) n
Answer: d
Explanation: Maximum number used in case of worst case.
