import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;
import java.time.Duration;
import java.time.Instant;
public class twoQueue {
public static void reverse(Queue<Integer> initQueue){
/**
* In order to reverse the Queue into a stack, you need to make a temporary/empty stack
* Then, reverse the queue order by popping the elements from the stack and put the elements into the queue into the stack
* Push the elements back into the Queue & print elements in the queue
*/
Stack<Integer> temp = new Stack<>(); //creates a temporary stack
//pushes element from queue to stack
while(!initQueue.isEmpty()){
temp.push(initQueue.poll());
}
//pop elements from stack to Queue
while(!temp.isEmpty())
{
initQueue.add(temp.pop());
}
//print values from queue
for(Integer value2: initQueue) {
System.out.print(value2 + " -> ");
}
System.out.print("nil");
}
public static void main(String[] args){
// Measure time it takes for reverse queue to run
int time = 0;
Queue<Integer> queue1 = new LinkedList<>();
final Duration timeElapsed;
Instant start = Instant.now(); // time capture -- start
// Add 100 elements to queue for reversing
for (int i = 0; i < 100; i++) {
queue1.add(i);
}
System.out.println("Initial Queue: "+ queue1);
System.out.print("Reverse Queue: ");
reverse(queue1);
Instant end = Instant.now(); // time capture -- end
timeElapsed = Duration.between(start, end);
System.out.println();
System.out.println("Nanoseconds: " + timeElapsed.getNano());
time += timeElapsed.getNano();
System.out.println("Total Nanoseconds: " + time );
System.out.println("Total Seconds: " + time /1000000000.0);
}
}
