Leetcode 232: Implement Queue using Stacks

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grid47
Exploring patterns and algorithms
Oct 14, 2024 6 min read

A series of stacks transforming into a queue, with elements gently flowing between them.
Solution to LeetCode 232: Implement Queue using Stacks Problem

Design and implement a queue using only two stacks. The queue should support the basic operations of a normal queue: enqueue, dequeue, peek, and checking if the queue is empty.
Problem
Approach
Steps
Complexity
Input: The input consists of several function calls to manipulate the queue. Each call is an operation on the queue object.
Example: Input: ["MyQueue", "enqueue", "enqueue", "peek", "dequeue", "empty"] [[], [5], [10], [], [], []]
Constraints:
• 1 <= x <= 9
• At most 100 calls will be made to enqueue, dequeue, peek, and empty.
• All dequeue and peek operations are valid.
Output: The output will be the result of the operations performed on the queue.
Example: Output: [null, null, null, 5, 5, false]
Constraints:
Goal: The goal is to use two stacks to simulate the FIFO behavior of a queue.
Steps:
• Use two stacks: s1 for enqueue operations and s2 for dequeue operations.
• For enqueue, push elements to s1.
• For dequeue and peek, transfer elements from s1 to s2 if s2 is empty, then perform the operation on s2.
Goal: The queue should be implemented using two stacks, and the operations must adhere to stack limitations (push, pop, peek).
Steps:
Assumptions:
• The input will consist of valid function calls for the queue.
• The operations enqueue, dequeue, peek, and empty will be called sequentially.
Input: Input: ["MyQueue", "enqueue", "enqueue", "peek", "dequeue", "empty"] [[], [5], [10], [], [], []]
Explanation: After pushing 5 and 10, the queue is [5, 10]. Peek returns 5, dequeue returns 5, and empty returns false because the queue is not empty.

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