用C语言实现循环单链表的就地逆置

可以使用以下代码实现循环单链表的就地逆置：

#include <stdio.h>
#include <stdlib.h>

typedef struct node {
    int data;
    struct node *next;
} Node;

Node *reverseList(Node *head) {
    if (head == NULL || head->next == NULL) {
        return head;
    }
    Node *prev = NULL;
    Node *curr = head;
    Node *next = head->next;
    while (next != head) {
        curr->next = prev;
        prev = curr;
        curr = next;
        next = next->next;
    }
    curr->next = prev;
    head->next = curr;
    return head;
}

int main() {
    Node *head = (Node *)malloc(sizeof(Node));
    head->next = head;
    Node *tail = head;
    for (int i = 1; i <= 5; i++) {
        Node *node = (Node *)malloc(sizeof(Node));
        node->data = i;
        node->next = head;
        tail->next = node;
        tail = node;
    }
    printf("Original list: ");
    Node *p = head->next;
    while (p != head) {
        printf("%d ", p->data);
        p = p->next;
    }
    printf("\n");
    head = reverseList(head);
    printf("Reversed list: ");
    p = head->next;
    while (p != head) {
        printf("%d ", p->data);
        p = p->next;
    }
    printf("\n");
    return ;
}

这个程序会创建一个循环单链表，然后调用 `reverseList` 函数对其进行就地逆置。最后输出原始链表和逆置后的链表。