public Question25() {
list = new LinkedList();
list.insert(1);
list.insert(3);
list.insert(5);
list.insert(7);
list.insert(8);
list.insert(10);
Node entry = list.root;
for (int i = 0; i < 3; i++) entry = entry.next;
Node last = list.root;
while (last.next != null) last = last.next;
last.next = entry;
}
public void remove(Node node) {
Node remove = node;
remove.data = node.next.data;
remove.next = node.next.next;
}
public static void hasLoop(Node first) {
// If list is empty no loop exists
if (first == null) {
System.out.println("List empty!");
}
// Set tortoise to the start of the list
Node tortoise = new Node(first.getElement(), first.getNext());
// Set hare to next element
Node hare = new Node(tortoise.getNext().getElement(), tortoise.getNext());
while (tortoise != hare) {
// Move tortoise one position
tortoise = tortoise.getNext();
// Move hare two positions
if (hare == null) {
System.out.println("No cycle found"); // reached the end, no cycle
break;
} else {
hare = hare.getNext().getNext();
}
// Cycle found
if (tortoise == hare) {
// Reset tortoise to start of list
tortoise = new Node(first.getElement(), first.getNext());
int mu = 0;
// Move tortoise and hare at one step each
// Tortoise and hare will intersect again at start of cycle
while (tortoise != hare) {
tortoise = tortoise.getNext();
hare = hare.getNext();
mu += 1;
}
hare = tortoise.getNext();
int lam = 1;
// Hare moves one step at a time until it meets tortoise
// to determine the lenght of the cycle
while (tortoise != hare) {
hare = hare.getNext();
lam += 1;
}
// Feedback
System.out.println("Cycle found!");
System.out.println("Cycle starts at: " + mu);
System.out.println("Cycle length: " + lam);
}
}
}