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Copy pathMyStack.java
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58 lines (49 loc) · 1.39 KB
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package stack;
import java.util.LinkedList;
import java.util.Queue;
class MyStack
{
private Queue<Integer> queueForPush = new LinkedList<>();
private Queue<Integer> queueForPop = new LinkedList<>();
// Push element x onto stack.
public void push(int x)
{
queueForPush.offer( x );
}
// Removes the element on top of the stack.
public void pop()
{
// dequeue elem from queueForPush and enqueue in queueForPop
while ( queueForPush.size() > 1 )
{
queueForPop.offer( queueForPush.poll() );
}
// dequeue elem from queueForPop and enqueue in queueForPush
while ( !queueForPop.isEmpty() )
{
queueForPush.offer( queueForPop.poll() );
}
}
// Get the top element.
public int top()
{
// dequeue elem from queueForPush and enqueue in queueForPop
int lastNumber = 0;
while ( !queueForPush.isEmpty() )
{
lastNumber = queueForPush.poll();
queueForPop.offer( lastNumber );
}
// dequeue elem from queueForPop and enqueue in queueForPush
while ( !queueForPop.isEmpty() )
{
queueForPush.offer( queueForPop.poll() );
}
return lastNumber;
}
// Return whether the stack is empty.
public boolean empty()
{
return queueForPush.isEmpty();
}
}