middleNode.go

/* https://leetcode.com/problems/middle-of-the-linked-list/
Given a non-empty, singly linked list with head node head, return a middle node of linked list.

If there are two middle nodes, return the second middle node.

Example 1:

	Input: [1,2,3,4,5]
	Output: Node 3 from this list (Serialization: [3,4,5])
	The returned node has value 3.  (The judge's serialization of this node is [3,4,5]).
	Note that we returned a ListNode object ans, such that:
	ans.val = 3, ans.next.val = 4, ans.next.next.val = 5, and ans.next.next.next = NULL.

Example 2:

	Input: [1,2,3,4,5,6]
	Output: Node 4 from this list (Serialization: [4,5,6])
	Since the list has two middle nodes with values 3 and 4, we return the second one.

Note:

	The number of nodes in the given list will be between 1 and 100.
*/

package lll

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func middleNode(head *ListNode) *ListNode {
	slow, fast := head, head
	for fast != nil && fast.Next != nil {
		slow, fast = slow.Next, fast.Next.Next
	}
	return slow
}