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
Solution
快慢指针：当快指针走到终点时慢指针所指的就是中间结点
- 奇数个结点是正好是中间结点
- 偶数个结点时是第一个中间结点
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* struct ListNode *next;
* };
*/
struct ListNode* middleNode(struct ListNode* head){
struct ListNode *fast, *slow;
fast = head->next;
slow = head;
while (fast && fast->next) {
fast = fast->next->next;
slow = slow->next;
}
if (fast == NULL) return slow;
else return slow->next;
}
