LeetCode(easy)-876.Middle of the Linked List

876.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.
題目：
給定具有頭節點頭的非空的單鏈表，返回鏈表的中間節點。
如果有兩個中間節點，則返回第二個中間節點。
解法一：

/**設置一快一慢指針，當快的指針到達結尾時，慢指針指向的就是結果
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */
struct ListNode* middleNode(struct ListNode* head) {
    struct ListNode* fast=head;
    struct ListNode* slow=head;
    while(fast&&fast->next){
        fast=fast->next->next;
        slow=slow->next;
    }
    return slow; 
}

Runtime: 0 ms