用c语言编写在带头结点的动态单链表和静态单链表上实现线性表操作LENGTH（L）的算法，并将长度写入头结点的数据域中

动态单链表实现：

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

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

typedef struct {
    Node* head;
} LinkedList;

int LENGTH(LinkedList* L) {
    int len = 0;
    Node* p = L->head->next;
    while (p != NULL) {
        len++;
        p = p->next;
    }
    L->head->data = len;
    return len;
}

int main() {
    LinkedList L;
    L.head = (Node*)malloc(sizeof(Node));
    L.head->data = 0; // 初始化头结点的数据域为0
    L.head->next = NULL;
    Node* p = L.head;
    // 尾插法创建链表
    for (int i = 1; i <= 5; i++) {
        Node* node = (Node*)malloc(sizeof(Node));
        node->data = i;
        node->next = NULL;
        p->next = node;
        p = node;
    }
    printf("链表长度为：%d\n", LENGTH(&L));
    printf("头结点的数据域为：%d\n", L.head->data);
    return 0;
}

静态单链表实现：

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

#define MAXSIZE 100

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

typedef struct {
    Node nodes[MAXSIZE];
    int head;
} LinkedList;

int LENGTH(LinkedList* L) {
    int len = 0;
    int p = L->head;
    while (p != -1) {
        len++;
        p = L->nodes[p].next;
    }
    L->nodes[0].data = len;
    return len;
}

int main() {
    LinkedList L;
    L.head = 1;
    // 初始化静态单链表
    for (int i = 1; i < MAXSIZE; i++) {
        L.nodes[i].next = i + 1;
    }
    L.nodes[MAXSIZE - 1].next = -1; // 最后一个结点的next为-1
    L.nodes[0].data = 0; // 初始化头结点的数据域为0

    int p = L.head;
    // 尾插法创建链表
    for (int i = 1; i <= 5; i++) {
        L.nodes[p].data = i;
        p = L.nodes[p].next;
    }
    printf("链表长度为：%d\n", LENGTH(&L));
    printf("头结点的数据域为：%d\n", L.nodes[0].data);
    return 0;
}