IIT-BHU-Anamika

Simulating queue using stack...

Problem statement: we are given one stack and we have to implement the queue using this stack means enqueue(insert into stack) and dequeue ( pop from stack) should behave as queue. No additional stack should be used.

This can be done using Operating system stack by using recursion.

public class SimulatedQueue < E > {
    private java.util.Stack < E > stack = 
                     new java.util.Stack < E >();

    public void insert(E elem) {
        if (!stack.empty()) {
            E topElem = stack.pop();
            insert(elem);
            stack.push(topElem);
        }
        else
            stack.push(elem);
    }

    public E remove() {
        return stack.pop();
    }
}