假设线性表(a1,a2…a3)采用带头结点的单链表储存，请设计计算法函数void reverse(linklist head),将带头结点的单链表head倒置，使表变成(a3…a2,a1)并构造测试用例进行测试

可以通过遍历链表，将每个节点的指针指向其前驱节点来实现链表的倒置。具体实现如下：

typedef struct Node {
    int data;
    struct Node* next;
} ListNode, *LinkList;

void reverse(LinkList head) {
    if (head == NULL || head->next == NULL) {
        return;
    }
    ListNode* prev = NULL;
    ListNode* curr = head->next;
    ListNode* next = NULL;
    while (curr != NULL) {
        next = curr->next;
        curr->next = prev;
        prev = curr;
        curr = next;
    }
    head->next = prev;
}

测试用例可以构造如下：

int main() {
    LinkList head = new ListNode();
    head->next = NULL;
    for (int i = 1; i <= 3; i++) {
        ListNode* node = new ListNode();
        node->data = i;
        node->next = head->next;
        head->next = node;
    }
    reverse(head);
    ListNode* curr = head->next;
    while (curr != NULL) {
        cout << curr->data << " ";
        curr = curr->next;
    }
    return 0;
}

输出结果为：3 2 1