LeetCode/java/linked-list-cycle.java

/**
 * Definition for singly-linked list. class ListNode { int val; ListNode next; ListNode(int x) { val
 * = x; next = null; } }
 */
public class Solution {
  public boolean hasCycle(ListNode head) {
    var x = head;
    var y = head;

    while (y != null && y.next != null) {
      x = x.next;
      y = y.next.next;

      if (x == y) {
        return true;
      }
    }

    return false;
  }
}