Engineering Questions with Answers - Multiple Choice Questions
Data Structure MCQ – Reverse a Word using Stack
1 - Question
Reversing a word using stack can be used to find if the given word is a palindrome or not.
a) True
b) False
View Answer
Answer: a
Explanation: This application of stack can also be used to find if the given word is a palindrome because, if the reversed is same as that of the original word, the given word is a palindrome.
2 - Question
Which is the most appropriate data structure for reversing a word?
a) queue
b) stack
c) tree
d) graph
View Answer
Answer: b
Explanation: Stack is the most appropriate data structure for reversing a word because stack follows LIFO principle.
3 - Question
Operations required for reversing a word or a string using stack are push() and pop().
a) True
b) False
View Answer
Answer: a
Explanation: Push operation inserts a character into the stack and pop operation pops the top of the stack.
4 - Question
What is the time complexity of reversing a word using stack algorithm?
a) O (N log N)
b) O (N2)
c) O (N)
d) O (M log N)
View Answer
Answer: c
Explanation: The time complexity of reversing a stack is mathematically found to be O (N) where N is the input.
5 - Question
What will be the word obtained if the word “abbcabb” is reversed using a stack?
a) bbabbca
b) abbcabb
c) bbacbba
d) bbacabb
View Answer
Answer: c
Explanation: The string “abbcabb” is pushed on to the stack. If the characters are popped one by one, the word obtained will be bbacbba.
6 - Question
How many stacks are required for reversing a word algorithm?
a) one
b) two
c) three
d) four
View Answer
Answer: a
Explanation: Only 1 stack is required for reversing a word using stack. In that stack, push and pop operations are carried out.
7 - Question
What will be result if the given stack is popped?
a) pat
b) tap
c) atp
d) apt
View Answer
Answer: b
Explanation: The word ‘pat’ is pushed on to the stack. When the characters of the stack are popped one by one, the word ‘tap’ is obtained.
8 - Question
What will be output if the following sequence of operations are executed?
Push(a,s); Push(b,s); Pop(b); Push(c,s);
a) abc
b) b
c) ac
d) acb
View Answer
Answer: b
Explanation: The element ‘b’ is popped out of the stack. Hence the output of the following sequence of operations will be ‘b’.
9 - Question
What are the set of functions that are to be executed to get the following output?
cat
a) push(c, s); push(a, s); push(t, s);
pop(s); pop(s); pop(s);
b) push(c,s); pop(s); push(a,s); pop(s);push(t,s);pop(s);
c) pop(c ); pop(a); pop(t);
d) push(c,s); push(a,s); pop(t);
View Answer
Answer: b
Explanation: During push operation, the characters ‘c’, ’a’, ’t’ are inserted into the stack and popped immediately after push.
10 - Question
How will your stack look like if the word ‘java’ is pushed?
a)
b)
c)
d)
View Answer
Answer: a
Explanation: When a character is pushed, it stays on the top of the stack. While popping, the word occurs in reverse order since stack follows LIFO principle.
11 - Question
Find the error (if any) in the following code snippet for pop operation.
void pop() //removing an element from a stack { printf(“%s”, stack[top++]); }
a) run time error
b) compile time error
c) pop operation is performed, but top moved in wrong direction
d) pop operation is performed properly
View Answer
Answer: c
Explanation: The statement printf(“%s”, stack[top++]) does a pop, but top gets incremented which is not correct. The statement stack[top++] should be replaced with stack[top–] in order to pop an operand and maintain stack properly.
12 - Question
What will be the output of the following program?
main() { char str[]="san foundry"; int len = strlen(str); int i; for(i=0;i<len;i++) push(str[i]); // pushes an element into stack for(i=0;i<len;i++) pop(); //pops an element from the stack }
a) sanfoundry
b) san foundry
c) yrdnuof nas
d) foundry nas
View Answer
Answer: c
Explanation: First, the string ‘san foundry’ is pushed one by one into the stack.
When it is popped, the output will be as ‘yrdnuof nas’.