如何在未知链表中找到一个中间节点

两个头指针，一个移动的快，一个移动的慢，当一个到达末尾时，另一个到达中间，代码如下:

struct Node{int value;struct Node *next;};

typedef struct Node ListNode;int search(ListNode *head){if(head == NULL)return;ListNode *fast = head;ListNode *low = head;while(fast->next != NULL){if(fast->next->next == NULL){fast=fast->next->next;low = low->next}else{fast = fast->next;low = low->next;}}return low->value;}