In a queue implemented using two stacks, what is the worst-case time complexity
Practice Questions
Q1
In a queue implemented using two stacks, what is the worst-case time complexity for the dequeue operation?
O(1)
O(n)
O(log n)
O(n^2)
Questions & Step-by-Step Solutions
In a queue implemented using two stacks, what is the worst-case time complexity for the dequeue operation?
Step 1: Understand what a queue is. A queue is a data structure that follows the First In First Out (FIFO) principle, meaning the first element added is the first one to be removed.
Step 2: Know that we are implementing a queue using two stacks. A stack is a data structure that follows the Last In First Out (LIFO) principle.
Step 3: Recognize that to dequeue (remove) an element from the queue, we need to access the oldest element that was added.
Step 4: When we want to dequeue, if the second stack (the one used for dequeueing) is empty, we need to transfer all elements from the first stack to the second stack.
Step 5: Understand that transferring elements means popping them from the first stack and pushing them onto the second stack, which takes time.
Step 6: If there are 'n' elements in the first stack, transferring all of them to the second stack takes O(n) time in the worst case.
Step 7: Therefore, the worst-case time complexity for the dequeue operation in this implementation is O(n).
