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Suppose you are given an implementation of a queue of integers. The operations that can be performed on the queue are:

  1. isEmpty (Q) — returns true if the queue is empty, false otherwise.
  2. delete (Q) — deletes the element at the front of the queue and returns its value.
  3. insert (Q, i) — inserts the integer i at the rear of the queue.

Consider the following function:

void f (queue Q) {
int i ;
if (!isEmpty(Q)) {
   i = delete(Q);
   f(Q);
   insert(Q, i);
  }
}

What operation is performed by the above function f ?

  1. Leaves the queue Q unchanged
  2. Reverses the order of the elements in the queue Q
  3. Deletes the element at the front of the queue Q and inserts it at the rear keeping the other elements in the same order
  4. Empties the queue Q
asked in DS by Veteran (18.3k points)   | 434 views

4 Answers

+11 votes
Best answer

insert() will inserts the value in just reverse order.

answered by Veteran (49.7k points)  
selected by
+5 votes
ans b)
answered by Boss (5.3k points)  
+4 votes
answer will be b.

explanation...

assume a queue of element 1 2 3 4 5...

now as Q is not empty it will delete 1 and 1 will be sored in i and den again f(Q) will be called which contains element 23456...but the trace (activation of inset (Q,1)) remains.it continues till 5 is deleted and again activation is executed by inserting q(5)...to q(1),,,thus reversing the queue
answered by Boss (8k points)  
is ny other better approach to understand it ?
0 votes
Answer: B
answered by Veteran (33.7k points)  
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