用c语言写环形链表。实现链表的删除

以下是用C语言实现环形链表的基本代码：

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

// 定义节点结构体
typedef struct node {
    int data;
    struct node *next;
} Node;

// 创建新节点
Node *new_node(int data) {
    Node *node = (Node *)malloc(sizeof(Node));
    node->data = data;
    node->next = NULL;
    return node;
}

// 添加节点到链表末尾
void add_node(Node **head, int data) {
    Node *node = new_node(data);
    if (*head == NULL) {
        *head = node;
        (*head)->next = *head;
    } else {
        Node *curr = *head;
        while (curr->next != *head) {
            curr = curr->next;
        }
        curr->next = node;
        node->next = *head;
    }
}

// 打印链表
void print_list(Node *head) {
    if (head == NULL) {
        printf("List is empty.\n");
    } else {
        Node *curr = head;
        do {
            printf("%d ", curr->data);
            curr = curr->next;
        } while (curr != head);
        printf("\n");
    }
}

// 删除节点
void delete_node(Node **head, int data) {
    if (*head == NULL) {
        printf("List is empty.\n");
        return;
    }
    Node *curr = *head;
    Node *prev = NULL;
    while (curr->data != data) {
        prev = curr;
        curr = curr->next;
        if (curr == *head) {
            printf("Node not found.\n");
            return;
        }
    }
    if (curr == *head && curr->next == *head) {
        *head = NULL;
    } else if (curr == *head) {
        Node *last = *head;
        while (last->next != *head) {
            last = last->next;
        }
        *head = (*head)->next;
        last->next = *head;
    } else {
        prev->next = curr->next;
    }
    free(curr);
}

int main() {
    Node *head = NULL;
    add_node(&head, 1);
    add_node(&head, 2);
    add_node(&head, 3);
    add_node(&head, 4);
    add_node(&head, 5);
    print_list(head);
    delete_node(&head, 3);
    print_list(head);
    delete_node(&head, 1);
    print_list(head);
    delete_node(&head, 5);
    print_list(head);
    return 0;
}

在这个代码中，我们通过定义一个指向自身的头节点来实现环形链表。添加节点时，我们遍历链表找到最后一个节点，然后将新节点添加到最后一个节点的后面，并将其指向头节点。删除节点时，我们遍历链表找到要删除的节点，并将其从链表中移除，然后释放内存。需要注意的是，如果要删除的是头节点，我们需要特殊处理。如果链表只有一个节点，我们将头节点设为NULL。