数据结构篇：单循环链表倒置（带头结点/不带头结点）

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带头结点

先去看一下单链表的倒置：https://blog.csdn.net/qq_15020543/article/details/84590642

对于单循环链表，它与单链表区别是，它的最后一个结点将指向头结点（无头结点将指向第一个结点），构成一个循环.

遍历循环链表的时候，结束标志是next指向head

理解了这些基础概念，单循环链表的倒置也不难了

完整函数

Inode *Test::ReserveLink(Inode *h) {
    Inode *HeadNext, *HeadPre, *firstNode;
    HeadNext = h->next->next;
    HeadPre = h->next;
    firstNode = h->next;//保存第一个结点的引用
    while (HeadNext != h)
    {
        Inode *tempNode = HeadNext->next;
        HeadNext->next = HeadPre;
        HeadPre = HeadNext;
        if (tempNode == h)
        {
            h->next = HeadPre;
        }
        HeadNext = tempNode;
    }
    //将最初的第一个结点，指向现在的头结点
    firstNode->next = h;
    return h;
}

 完整程序

#include <iostream>

using namespace std;

typedef struct Link {
    int num;
    Link *next;
} Inode;

class Test {
public :
    Inode *t_CreateList(Inode *Head, int n);//尾插法建立单循环链表
    void ShowLink(Inode *h);

    Inode *ReserveLink(Inode *h);
};

Inode *Test::t_CreateList(Inode *Head, int n) {
    Inode *p = Head;
    for (int i = 0; i < n; i++)
    {
        Inode *s = new Inode;
        cin >> s->num;
        s->next = p->next;
        p->next = s;
        p = s;
    }
    return Head;
}


void Test::ShowLink(Inode *h) {
    Inode *p = h;
    cout << "单循环链表为：" << endl;
    while (p->next != h)
    {
        cout << p->next->num << "-->";
        p = p->next;
    }
    cout << endl;
}

Inode *Test::ReserveLink(Inode *h) {
    Inode *HeadNext, *HeadPre, *firstNode;
    HeadNext = h->next->next;
    HeadPre = h->next;
    firstNode = h->next;//保存第一个结点的引用
    while (HeadNext != h)
    {
        Inode *tempNode = HeadNext->next;
        HeadNext->next = HeadPre;
        HeadPre = HeadNext;
        if (tempNode == h)
        {
            h->next = HeadPre;
        }
        HeadNext = tempNode;
    }
    //将最初的第一个结点，指向现在的头结点
    firstNode->next = h;
    return h;
}

int main() {
    Test test;
    Inode *Head = new Inode;
    Head->next = Head;
    int num;
    cout << "您想要创建几个元素的单循环链表？请输入：" << endl;
    cin >> num;
    Head = test.t_CreateList(Head, num);
    test.ShowLink(Head);
    Head = test.ReserveLink(Head);
    test.ShowLink(Head);
    return 0;
}

运行截图

不带头结点

Inode *Test::ReserveLink(Inode *h) {
    Inode *HeadNext, *HeadPre, *firstNode;
    HeadNext = h->next;
    HeadPre = h;
    firstNode = h;//保存第一个结点的引用
    while (HeadNext != h)
    {
        Inode *tempNode = HeadNext->next;
        HeadNext->next = HeadPre;
        HeadPre = HeadNext;
        if (tempNode == h)
        {
            h = HeadPre;
        }
        HeadNext = tempNode;
    }
    //将最初的第一个结点，指向现在的头结点
    firstNode->next = h;
    return h;
}