字符串采用链式存储结构，设计求子串的算法；代码

以下是一个求子串的算法，采用了链式存储结构。

// 定义链表节点结构体
typedef struct ListNode {
    char data;
    struct ListNode* next;
} ListNode;

// 定义链表结构体
typedef struct {
    ListNode* head;
    int length;
} LinkedList;

// 初始化链表
void initLinkedList(LinkedList* list) {
    list->head = NULL;
    list->length = 0;
}

// 在链表尾部插入元素
void insertNode(LinkedList* list, char data) {
    ListNode* node = (ListNode*)malloc(sizeof(ListNode));
    node->data = data;
    node->next = NULL;
    if (list->head == NULL) {
        list->head = node;
    } else {
        ListNode* p = list->head;
        while (p->next != NULL) {
            p = p->next;
        }
        p->next = node;
    }
    list->length++;
}

// 从链表中删除指定位置的节点
void deleteNode(LinkedList* list, int index) {
    if (index < 0 || index >= list->length) {
        return;
    }
    if (index == 0) {
        ListNode* p = list->head;
        list->head = p->next;
        free(p);
    } else {
        ListNode* p = list->head;
        for (int i = 0; i < index - 1; i++) {
            p = p->next;
        }
        ListNode* q = p->next;
        p->next = q->next;
        free(q);
    }
    list->length--;
}

// 求子串
LinkedList* getSubString(LinkedList* list, int start, int end) {
    if (start < 0 || start >= list->length || end < 0 || end >= list->length || start > end) {
        return NULL;
    }
    LinkedList* subList = (LinkedList*)malloc(sizeof(LinkedList));
    initLinkedList(subList);
    ListNode* p = list->head;
    for (int i = 0; i < start; i++) {
        p = p->next;
    }
    for (int i = start; i <= end; i++) {
        insertNode(subList, p->data);
        p = p->next;
    }
    return subList;
}

使用示例：

int main() {
    LinkedList list;
    initLinkedList(&list);
    insertNode(&list, 'a');
    insertNode(&list, 'b');
    insertNode(&list, 'c');
    insertNode(&list, 'd');
    insertNode(&list, 'e');
    LinkedList* subList = getSubString(&list, 1, 3);
    ListNode* p = subList->head;
    while (p != NULL) {
        printf("%c ", p->data);
        p = p->next;
    }
    return 0;
}

输出结果：

b c d