876.Middle of the Linked List
===

###### tags: `Easy`,`Linked List`,`Two Pointers`

[876. Middle of the Linked List](https://leetcode.com/problems/middle-of-the-linked-list/)

### 題目描述

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.

### 範例

**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`

### 解答
#### Python

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def middleNode(self, head: Optional[ListNode]) -> Optional[ListNode]:
        slow = fast = head
        
        while fast and fast.next:
            slow, fast = slow.next, fast.next.next
            
        return slow

> [name=Kobe][time= Dec 5, 2022]

#### Javascript

function middleNode(head) {
  let slow = head;
  let fast = head;
  while (fast && fast.next) {
    slow = slow.next;
    fast = fast.next.next;
  }

  return slow;
}

> [name=Marsgoat][time= Dec 5, 2022]

#### C#

public class Solution {
    public ListNode MiddleNode(ListNode head) {
        var slow = head;
        var fast = head;
        
        while (fast.next != null) {
            slow = slow.next;
            fast = fast.next;
            
            if (fast.next == null) break;
                
            fast = fast = fast.next;
        }
        
        return slow;
    }
}

> [name=Jim][time= Dec 5, 2022]

### Reference

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