Design-2/MyQueue.java at master · Amaan-29/Design-2 · GitHub

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import java.util.Stack;

public class MyQueue {

    private Stack<Integer> in;
    private Stack<Integer> out;

    public MyQueue() {
        this.in = new Stack<>();
        this.out = new Stack<>();
    }

    public void push(int x) {
        in.push(x); //add elements in IN stack
    }

    public int pop() {
        if(out.isEmpty()){
            while(!in.isEmpty()){
                out.push(in.pop());
            }
        }
        return out.pop();
    }

    public int peek() {
        if(out.isEmpty()){
            while(!in.isEmpty()){
                out.push(in.pop());
            }
        }
        return out.peek();
    }

    public boolean empty() {
        return in.isEmpty() && out.isEmpty();
    }
}