GATE | GATE-CS-2016 (Set 1) | Question 51
Let Q denote a queue containing sixteen numbers and S be an empty stack. Head(Q) returns the element at the head of the queue Q without removing it from Q. Similarly Top(S) returns the element at the top of S without removing it from S. Consider the algorithm given below.
The maximum possible number of iterations of the while loop in the algorithm is______
[This Question was originally a Fill-in-the-Blanks question]
(A) 16
(B) 32
(C) 256
(D) 64
Answer: (C)
Explanation: The worst case happens when the queue is sorted in decreasing order. In worst case, loop runs n*n times.
Queue: 4 3 2 1 Stack: Empty 3 2 1 4 3 2 1 4 Empty 2 1 4 3 2 1 4 3 Empty 1 4 3 2 1 4 3 2 Empty 4 3 2 1 3 2 1 4 3 2 4 1 2 4 1 3 2 4 3 1 4 3 1 2 3 1 2 4 3 4 1 2 4 1 2 3 Empty 1 2 3 4
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