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stackUsing2QueuePopc.java
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90 lines (82 loc) · 1.86 KB
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import java.util.*;
import java.util.Stack;
//pop costly
class stackUsing2QueuePopc
{
Queue<Integer> q1=new LinkedList<>();
Queue<Integer> q2=new LinkedList<>();
int size;
public stackUsing2QueuePopc()
{
int size=0;
}
public void push(int x)
{
q1.add(x);
size++;
}
public void pop()
{
if (q1.isEmpty())
{
return;
}
while(q1.size()!=1)
{
q2.add(q1.peek());
q1.remove();
}
q1.remove();
size--;
// swap the names of two queues
Queue<Integer> q = q1;
q1 = q2;
q2 = q;
}
public int size()
{
return size;
}
public int top()
{
if(q1.isEmpty())
{
return -1;
}
while(q1.size()!=1)
{
q2.add(q1.peek());
q1.remove();
}
int temp=q1.peek();
q1.remove();
q2.add(temp);
// swap the names of two queues
Queue<Integer> q = q1;
q1 = q2;
q2 = q;
return temp;
}
public static void main(String[] args)
{
stackUsing2QueuePopc s=new stackUsing2QueuePopc();
s.push(2);
s.push(5);
s.push(7);
s.push(9);
System.out.println("current size: " + s.size());
System.out.println(s.top());
s.pop();
System.out.println("current size: " + s.size());
System.out.println(s.top());
s.pop();
System.out.println("current size: " + s.size());
System.out.println(s.top());
s.pop();
System.out.println("current size: " + s.size());
System.out.println(s.top());
s.pop();
System.out.println("current size: " + s.size());
System.out.println(s.top());
}
}