cycle.java

public class cycle extends llpain {
    public static boolean isCycle() {
        Node slow = head;
        Node fast = head;
        while (fast != null && fast.next != null) {
            slow = slow.next;
            fast = fast.next.next;
            if (slow == fast)
                return true;
        }
        return false;
    }

    public static void removeC() {
        Node slow = head;
        Node fast = head;
        boolean cycle = false;
        while (fast != null && fast.next != null) {
            slow = slow.next;
            fast = fast.next.next;
            if (fast == slow) {
                cycle = true;
                break;
            }
        }
        if (cycle == false)
            return;
        slow = head; // find meet
        Node prev = null; // last node
        while (slow != fast) {
            prev = fast;
            slow = slow.next;
            fast = fast.next;
        }
        prev.next = null; // remove cycle as last->next=null
    }

    public static void main(String[] args) {
        head = new Node(1);
        Node temp = new Node(2);
        head.next = temp;
        head.next.next = new Node(3);
        head.next.next.next = temp;
        System.out.println(isCycle());
        removeC();
        System.out.println(isCycle());
    }
}