876. Middle of the Linked List

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