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Main.java
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Main.java
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/*
* Implementation of Stack using two Queue
*/
package stackUsingQueues;
import java.util.*;
class Stack{ // Stack class where all methods of stack are created
Queue<Integer> q1 = new LinkedList<Integer>();
Queue<Integer> q2 = new LinkedList<Integer>();
//using Push Operation costly approach
void push(int element) {
q2.add(element); //adding recently entered element to q2
while (!q1.isEmpty()) {
q2.add(q1.peek()); // moving all the elements of q1 to q2
q1.remove();
}
Queue<Integer> temp = q1;
q1 = q2; //swapping the queues
q2 = temp;
}
int pop() { // returns and remove the recently entered element
if (q1.isEmpty()) {
return -1; } //returns -1 for empty queue
else{
return q1.remove();
}
}
}
public class Main { //Main class
public static void main(String[] args) {
Scanner input=new Scanner (System.in);
Stack stack=new Stack(); //Instantiating Stack class
stack.push(2);
stack.push(3);
System.out.print(stack.pop()+" ");
stack.push(4);
System.out.print(stack.pop()+" ");
input.close();
}
}