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Problem Brief

Implement Queue using Stacks (Round 2, LC 232:)

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  • Round 1: Word Pattern II 🦭
  • Round 2: Implement Queue using Stacks 🦥
  • Round 3: Island Perimeter 🦉

    • I highly recommend to go to LC to solve this quesiton..

    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).

    Implement the MyQueue class:

    • void push(int x) Pushes element x to the back of the queue.
    • int pop() Removes the element from the front of the queue and returns it.
    • int peek() Returns the element at the front of the queue.
    • boolean empty() Returns true if the queue is empty, false otherwise.

    Notes:

    • You must use only standard operations of a stack, which means only push to top, peek/pop from top, size, and is empty operations are valid.
    • Depending on your language, the stack may not be supported natively. You may simulate a stack using a list or deque (double-ended queue) as long as you use only a stack's standard operations.

    🌟 Wallz carries one more time! 👏

    1Example 1

    Input
    operations = ["MyQueue", "push", "push", "peek", "pop", "empty"], arguments = [[], [1], [2], [], [], []]
    Output
    [null, null, null, 1, 1, false]
    Explanation

    MyQueue myQueue = new MyQueue(); myQueue.push(1); // queue is: [1] myQueue.push(2); // queue is: [1, 2] (leftmost is front of the queue) myQueue.peek(); // return 1 myQueue.pop(); // return 1, queue is [2] myQueue.empty(); // return false

    Constraints

    Limits and guarantees your solution can rely on.

    • 1 <= x <= 9
    • At most 100 calls will be made to push, pop, peek, and empty.
    • All the calls to pop and peek are valid.
    class MyQueue {
    // write your code here
    push(x: number): void {
        
    }

    pop(): number {
        
    }

    peek(): number {
        
    }

    empty(): boolean {
        
    }
}
    Input

    operations

    ["MyQueue", "push", "push", "peek", "pop", "empty"]

    arguments

    [[], [1], [2], [], [], []]

    Output

    ["null", "null", "null", "1", "1", "false"]

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