If a queue is implemented using two stacks, what is the time complexity of deque

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Question: If a queue is implemented using two stacks, what is the time complexity of dequeue operation in the worst case?

Options:

Correct Answer: O(n)

Solution:

In the worst case, the dequeue operation can take O(n) time because all elements may need to be transferred from one stack to another.

If a queue is implemented using two stacks, what is the time complexity of dequeue operation in the worst case?

If a queue is implemented using two stacks, what is the time complexity of dequeue operation in the worst case?

Step 1: Understand what a queue is. A queue is a data structure that follows the First In First Out (FIFO) principle.
Step 2: Understand what a stack is. A stack is a data structure that follows the Last In First Out (LIFO) principle.
Step 3: Learn how to implement a queue using two stacks. One stack is used for enqueue (adding elements) and the other for dequeue (removing elements).
Step 4: When you want to dequeue an element, check if the second stack (the dequeue stack) is empty.
Step 5: If the dequeue stack is empty, transfer all elements from the first stack (the enqueue stack) to the second stack. This reverses the order of elements.
Step 6: After transferring, the top of the second stack will be the front of the queue, so you can pop it off to dequeue.
Step 7: In the worst case, if you have 'n' elements in the first stack, you will need to transfer all 'n' elements to the second stack, which takes O(n) time.
Step 8: Therefore, the time complexity of the dequeue operation in the worst case is O(n).

Queue Implementation – Understanding how a queue can be implemented using two stacks and the implications for time complexity.
Time Complexity Analysis – Analyzing the time complexity of operations in data structures, particularly in the context of worst-case scenarios.