用类C语言设计算法实现循环单链表就地逆置

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

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

void init(Node** head, int n) {
*head = (Node*)malloc(sizeof(Node));
(*head)->data = 1;
(*head)->next = NULL;

Node* ptr = *head;
for (int i = 2; i <= n; i++) {
Node* newNode = (Node*)malloc(sizeof(Node));
newNode->data = i;
newNode->next = NULL;

ptr->next = newNode;
ptr = ptr->next;
}
ptr->next = *head; // 链接成循环链表
}

void printList(Node* head) {
Node* ptr = head;
do {
printf("%d ", ptr->data);
ptr = ptr->next;
} while (ptr != head);
}

void reverseList(Node** head) {
if (*head == NULL || (*head)->next == NULL) {
return;
}

Node* prev = NULL;
Node* cur = *head;
Node* nxt = (*head)->next;
do {
cur->next = prev;
prev = cur;
cur = nxt;
nxt = nxt->next;
} while (cur != *head);

(*head)->next = prev;
*head = prev;
}

int main() {
Node* head = NULL;
int n = 5;
init(&head, n);

printf("原始链表数据：\n");
printList(head);

reverseList(&head);
printf("\n逆置后的链表数据：\n");
printList(head);

return 0;
}备注：此算法实现了循环单链表的就地逆置，可供参考。