public static bool HasCircle(LeetCode141Node head)
{
if (head == null)
{
return(false);
}
var slow = head;
var fast = head;
while (fast != null && fast.next != null)
{
// fast go two steps each time
fast = fast.next.next;
// slow go one step each time
slow = slow.next;
if (fast == slow)
{
return(true);
}
}
return(false);
}
public LeetCode141Node(int x)
{
val = x;
next = null;
}