循環(huán)鏈表中的最后一個(gè)節(jié)點(diǎn)的指針指向第一個(gè)節(jié)點(diǎn)，形成一個(gè)閉環(huán)。可以快速進(jìn)行在頭部或尾部插入和刪除節(jié)點(diǎn)的操作。循環(huán)鏈表可以從任意節(jié)點(diǎn)開始遍歷，可以順時(shí)針或逆時(shí)針遍歷整個(gè)鏈表。

代碼：

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

// 定義鏈表節(jié)點(diǎn)結(jié)構(gòu)
struct Node {
    int data;           // 數(shù)據(jù)域
    struct Node* next;  // 指向下一個(gè)節(jié)點(diǎn)的指針
};

// 初始化循環(huán)鏈表
void initCircularList(struct Node** head) {
    *head = NULL;  // 將頭指針置為空，表示鏈表為空
}

// 在循環(huán)鏈表末尾添加節(jié)點(diǎn)
void appendCircularNode(struct Node** head, int data) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->next = NULL;

    if (*head == NULL) {
        *head = newNode;
        newNode->next = *head;  // 將新節(jié)點(diǎn)的next指針指向自身，形成循環(huán)
    } else {
        struct Node* temp = *head;
        while (temp->next != *head) {
            temp = temp->next;
        }
        temp->next = newNode;
        newNode->next = *head;
    }
}

// 在循環(huán)鏈表指定位置插入節(jié)點(diǎn)
void insertCircularNode(struct Node** head, int data, int position) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->next = NULL;

    if (position == 0) {
        newNode->next = *head;
        struct Node* temp = *head;
        while (temp->next != *head) {
            temp = temp->next;
        }
        temp->next = newNode;
        *head = newNode;
    } else {
        struct Node* temp = *head;
        int count = 0;
        while (temp->next != *head && count < position - 1) {
            temp = temp->next;
            count++;
        }
        if (count < position - 1) {
            printf("Invalid position\n");
            return;
        }
        newNode->next = temp->next;
        temp->next = newNode;
    }
}

// 刪除循環(huán)鏈表指定位置的節(jié)點(diǎn)
void deleteCircularNode(struct Node** head, int position) {
    if (*head == NULL) {
        printf("List is empty\n");
        return;
    }

    struct Node* temp = *head;
    if (position == 0) {
        while (temp->next != *head) {
            temp = temp->next;
        }
        if (temp == *head) {
            *head = NULL;
        } else {
            temp->next = (*head)->next;
            *head = (*head)->next;
        }
        free(temp);
    } else {
        int count = 0;
        struct Node* prev = NULL;
        while (temp->next != *head && count < position) {
            prev = temp;
            temp = temp->next;
            count++;
        }
        if (count < position) {
            printf("Invalid position\n");
            return;
        }
        prev->next = temp->next;
        free(temp);
    }
}

// 打印循環(huán)鏈表
void printCircularList(struct Node* head) {
    if (head == NULL) {
        printf("List is empty\n");
        return;
    }

    struct Node* temp = head;
    do {
        printf("%d ", temp->data);
        temp = temp->next;
    } while (temp != head);
    printf("\n");
}

// 釋放循環(huán)鏈表內(nèi)存
void freeCircularList(struct Node* head) {
    if (head == NULL) {
        return;
    }

    struct Node* temp = head;
    struct Node* nextNode;
    do {
        nextNode = temp->next;
        free(temp);
        temp = nextNode;
    } while (temp != head);
}

int main() {
    struct Node* head;
    initCircularList(&head);

    // 在循環(huán)鏈表末尾添加節(jié)點(diǎn)
    appendCircularNode(&head, 10);
    appendCircularNode(&head, 20);
    appendCircularNode(&head, 30);