LeetCode141.go

package main

func detectCycle(head *ListNode) *ListNode {
	if head == nil || head.Next == nil {
		return nil
	}
	fast , slow := head , head
	for {
		if fast == nil || fast.Next == nil {
			return nil
		}
		fast = fast.Next.Next
		slow = slow.Next
		if fast == slow {
			break ;
		}
	}
	fast = head
	for fast != slow {
		fast = fast.Next
		slow = slow.Next
	}
	return fast
}

func main() {

}