求链表的中间结点

常规解法

力扣链接: https://leetcode-cn.com/problems/middle-of-the-linked-list/
求链表长度法

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */
 int GetLengthOfList(struct ListNode* head)//获取长度
{
    
    
	int len = 0;
	while (head != NULL)
	{
    
    
		len++;
		head = head->next;
	}
	return len;
}

struct ListNode* middleNode(struct ListNode* head)
{
    
    
	int len = GetLengthOfList(head);
	struct ListNode* p = head;
	for (int i = 0; i<len / 2; i++)
	{
    
    
		p = p->next;
	}
	return p;
}

快慢指针法

struct ListNode* middleNode(struct ListNode* head)
{
    
    
    struct ListNode* fast,* slow;
    fast = slow = head;
    while(fast && fast->next != NULL)
    {
    
    
        fast = fast->next->next;
        slow = slow->next;
    }
    return slow;
}