In a queue implemented using two stacks, what is the time complexity of the dequeue operation in the worst case?
Practice Questions
1 question
Q1
In a queue implemented using two stacks, what is the time complexity of the dequeue operation in the worst case?
O(1)
O(n)
O(log n)
O(n log n)
In the worst case, the dequeue operation may require transferring all elements from one stack to another, resulting in O(n) time complexity.
Questions & Step-by-step Solutions
1 item
Q
Q: In a queue implemented using two stacks, what is the time complexity of the dequeue operation in the worst case?
Solution: In the worst case, the dequeue operation may require transferring all elements from one stack to another, resulting in O(n) time complexity.
Steps: 8
Step 1: Understand what a queue is. A queue is a data structure that follows the First In First Out (FIFO) principle.
Step 2: Know that we can implement a queue using two stacks. A stack is a data structure that follows the Last In First Out (LIFO) principle.
Step 3: Identify the two stacks: let's call them Stack A and Stack B.
Step 4: When we want to dequeue (remove an element from the front of the queue), we need to check if Stack B is empty.
Step 5: If Stack B is empty, we need to transfer all elements from Stack A to Stack B. This means popping each element from Stack A and pushing it onto Stack B.
Step 6: The transfer of elements from Stack A to Stack B takes time proportional to the number of elements in Stack A, which is O(n) in the worst case.
Step 7: If Stack B is not empty, we can simply pop the top element from Stack B, which takes O(1) time.
Step 8: Therefore, in the worst case, the dequeue operation requires transferring all elements from Stack A to Stack B, resulting in O(n) time complexity.
