Implement Queue using Stacks — Easy Coding Interview Question

Implement a first in first out (FIFO) queue using only two stacks. The implemented queue should support all the functions of a normal queue (push, peek, pop, and empty).

Example

Input: MyQueue q = new MyQueue(); q.push(1); q.push(2); q.peek(); // 1; q.pop(); // 1; q.empty(); // false

Output: [null, null, null, 1, 1, false]

Constraints

• 1 ≤ x ≤ 9
• At most 100 calls will be made to push, pop, peek, and empty

Topics & Companies

Topics: queue, stack

Asked by: Amazon, Microsoft, Google, Meta, Bloomberg

Optimal Solution Complexity

Time complexity: O(1) Amortized. Space complexity: O(n).

Practice more

• All DSA Problems
• DSA Patterns