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class Link {
public int iData;
public Link next;
public Link(int id) {
iData = id;
}
public String toString() {
return "{" + iData + "} ";
}
}
class FirstLastList {
private Link first;
private Link last;
public FirstLastList() {
first = null;
last = null;
}
public boolean isEmpty() {
return first == null;
}
public void insertFirst(int dd) {
Link newLink = new Link(dd);
if (isEmpty())
last = newLink;
newLink.next = first;
first = newLink;
}
public void insertLast(int dd) {
Link newLink = new Link(dd);
if (isEmpty())
first = newLink;
else
last.next = newLink;
last = newLink;
}
public int deleteFirst() {
int temp = first.iData;
if (first.next == null)
last = null;
first = first.next;
return temp;
}
public String toString() {
String str = "";
Link current = first;
while (current != null) {
str += current.toString();
current = current.next;
}
return str;
}
}
public class MainClass {
public static void main(String[] args) {
FirstLastList theList = new FirstLastList();
theList.insertFirst(22);
theList.insertFirst(44);
theList.insertFirst(66);
theList.insertLast(11);
theList.insertLast(33);
theList.insertLast(55);
System.out.println(theList);
theList.deleteFirst();
theList.deleteFirst();
System.out.println(theList);
}
}
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