142. Linked list cycle II

//142. Linked list cycle II

class ListNode {
    int val;
    ListNode next;
    ListNode(int x) {
        val = x;
        next = null;
    }
}

public class Solution {
    public ListNode detectCycle(ListNode head) {
        ListNode slowp = head;
        ListNode fastp = head;

        while(fastp != null && fastp.next != null) {
            slowp = slowp.next;
            fastp = fastp.next.next;

            if(slowp == fastp) {
                slowp = head;
                
                while(slowp != fastp) {
                    slowp = slowp.next;
                    fastp = fastp.next;
                }

                return slowp;
            }
        }

        return null;
    }
}