876. Middle of the Linked List

Easy

Given the head of a singly linked list, return the middle node of the linked list.

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

Example 1:

Input: head = [1,2,3,4,5]
Output:
 [3,4,5]
Explanation:
 The middle node of the list is node 3.

Example 2:

Input: head = [1,2,3,4,5,6]
Output:
 [4,5,6]
Explanation:
 Since the list has two middle nodes with values 3 and 4, we return the second one.

Constraints:

• The number of nodes in the list is in the range [1, 100].

• 1 <= Node.val <= 100

解題

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