链表逆序

实现链表逆序的功能

下面是实现链表逆序的函数：

/*
 * 把head指针指向的链表逆序
 * author:rio_2607
 */
void inverse(struct node *head)
{
    struct node *current = head;
    struct node *current_next = NULL;

    //如果是一个空链表或者只有一个元素,则直接返回
    if(NULL == head || NULL == current->next)
        return;

    current_next = current->next;

    while(current_next->next != NULL)
    {
        struct node *temp = current_next->next;
        current_next->next = current;//逆序指针

        current = current_next;//两个指针都往后移一个
        current_next = temp;
    }

    //把最后两个节点逆序
    current_next->next = current;
    head->next = NULL;

    head = current_next;//把头指针指向最后一个指针


    //打印输出结果
    struct node *t = head;
    while(t != NULL)
    {
        cout << t->data << "  ";
        t = t->next;
    }

}

其中，struct node的定义是：

struct node {
    int data;
    struct node *next;
};

下面是测试代码：先输入链表的长度，在依次输入每个链表的数据域的数据，然后分别打印输出逆序前后的数据：

int main()
{
    struct node *head = NULL;
    struct node *current = NULL;
    int number;
    cout << "please enter the number :" ;
    cin >> number;
    for(int i = 1;i <=number;++i)
    {
        struct node *temp = (struct node*)new struct node;
        cin >> temp->data;
        temp->next = NULL;

        if(NULL == head)
            head = temp;
        else
            current->next = temp;

        current = temp;

    }


    //打印数据
    struct node *t = head;
    cout << "Before inverse:" << endl;
    while(t != NULL)
    {
        cout << t->data << "  ";
        t = t->next;
    }

    cout << endl;

    cout << "After inverse:" << endl;

    inverse(head);//链表逆序

    return 0;
}

运行结果如下所示：