数据结构 C 代码 2.3: 双向链表

摘要: 双向链表比单链表稍复杂, 也更不常用. 主要是为了练习链表的变种, 寻找更多设计的感觉. 这样在面对实际问题的时候, 就具有一定的建模能力.

#include 
#include 


typedef struct DoubleLinkedNode{
	char data;
	struct DoubleLinkedNode *previous;
	struct DoubleLinkedNode *next;
} DLNode, *DLNodePtr;


DLNodePtr initLinkList(){
	DLNodePtr tempHeader = (DLNodePtr)malloc(sizeof(struct DoubleLinkedNode));
	tempHeader->data = '';
	tempHeader->previous = NULL;
	tempHeader->next = NULL;
	return tempHeader;
}// Of initLinkList


void printList(DLNodePtr paraHeader){
	DLNodePtr p = paraHeader->next;
	while (p != NULL) {
		printf("%c", p->data);
		p = p->next;
	}// Of while
	printf("rn");
}// Of printList


void insertElement(DLNodePtr paraHeader, char paraChar, int paraPosition){
	DLNodePtr p, q, r;

	// Step 1. Search to the position.
	p = paraHeader;
	for (int i = 0; i < paraPosition; i ++) {
		p = p->next;
		if (p == NULL) {
			printf("The position %d is beyond the scope of the list.", paraPosition);
			return;
		}// Of if
	} // Of for i

	// Step 2. Construct a new node.
	q = (DLNodePtr)malloc(sizeof(struct DoubleLinkedNode));
	q->data = paraChar;

	// Step 3. Now link.
	r = p->next;
	q->next = p->next;
	q->previous = p;
	p->next = q;
	if (r != NULL) {
		r->previous = q;
	}// Of if
}// Of insertElement


void deleteElement(DLNodePtr paraHeader, char paraChar){
	DLNodePtr p, q, r;
	p = paraHeader;

	// Step 1. Locate.
	while ((p->next != NULL) && (p->next->data != paraChar)){
		p = p->next;
	}// Of while

	// Step 2. Error check.
	if (p->next == NULL) {
		printf("The char '%c' does not exist.rn", paraChar);
		return;
	}// Of if

	// Step 3. Change links.
	q = p->next;
	r = q->next;
	p->next = r;
	if (r != NULL) {
		r->previous = p;
	}// Of if

	// Step 4. Free the space.
	free(q);
}// Of deleteElement


void insertDeleteTest(){
	// Step 1. Initialize an empty list.
	DLNodePtr tempList = initLinkList();
	printList(tempList);

	// Step 2. Add some characters.
	insertElement(tempList, 'H', 0);
	insertElement(tempList, 'e', 1);
	insertElement(tempList, 'l', 2);
	insertElement(tempList, 'l', 3);
	insertElement(tempList, 'o', 4);
	insertElement(tempList, '!', 5);
	printList(tempList);

	// Step 3. Delete some characters (the first occurrence).
	deleteElement(tempList, 'e');
	deleteElement(tempList, 'a');
	deleteElement(tempList, 'o');
	printList(tempList);

	// Step 4. Insert to a given position.
	insertElement(tempList, 'o', 1);
	printList(tempList);
}// Of appendInsertDeleteTest


void basicAddressTest(){
	DLNode tempNode1, tempNode2;

	tempNode1.data = 4;
	tempNode1.next = NULL;

	tempNode2.data = 6;
	tempNode2.next = NULL;

	printf("The first node: %d, %d, %drn",
		&tempNode1, &tempNode1.data, &tempNode1.next);
	printf("The second node: %d, %d, %drn",
		&tempNode2, &tempNode2.data, &tempNode2.next);

	tempNode1.next = &tempNode2;
}// Of basicAddressTest


void main(){
	insertDeleteTest();
	basicAddressTest();
}// Of main

Hello!
The char 'a' does not exist.
Hll!
Holl!
The first node: 1703632, 1703632, 1703640
The second node: 1703620, 1703620, 1703628
Press any key to continue

1. 仅实现了打印、插入、删除.
2. 每个相关指针都要改, 必须画个图来辅助写程序.
3. 尾结点删除时需要注意. 需要进行边界测试.

1. 抄代码.
2. 进行 insertElement 等函数进一步的测试.
3. 自己实现 locateElement 函数.
4. 挑本贴 bug 并留言.
5. 写 CSDN 博客. 必须有图示, 可以用工具画, 或者手绘拍照.

麦尔哈巴·阿卜杜拉同学的代码, 注释写得详细.

#include
using namespace std;
typedef int Status;
typedef int ElemType;
#define OVERFLOW -1
#define ERROR 0
#define OK 1

//-----双向链表的储存结构-----
typedef struct DuLNode
{
    ElemType data;
    struct DuLNode *prior;
    struct DuLNode *next;
} DuLNode, *DuLinkList;

DuLinkList L;

//1、双向链表初始化
Status InitList_DuL(DuLinkList &L)
{
    //构造一个空的双向链表L
    L = new DuLNode;
    L->prior = NULL;
    L->next = NULL;
    return OK;
}

//2、双向链表按位查找
DuLNode *GetElem_DuL(DuLinkList L, int i)
{
    DuLNode *p = L->next;
    int j = 1;
    while(p && j < i)
    {
        p = p->next;
        j++;
    }
    if(!p || j > i)
        return NULL;
    else
        return p;
}

//3、双向链表前驱
Status PriorElem_DuL(DuLinkList L, ElemType cur_e, ElemType &pre_e)
{
    DuLNode *p;
    if(!(p = LocateElem_DuL(L, cur_e)))                //在L中确定第i个元素的位置指针p
        return ERROR;
    pre_e = p->prior->data;
    return OK;
}

//4、双向链表后继
Status NextElem_DuL(DuLinkList L, ElemType cur_e, ElemType &next_e)
{
    DuLNode *p;
    if(!(p = LocateElem_DuL(L, cur_e)))                //在L中确定第i个元素的位置指针p
        return ERROR;
    next_e = p->next->data;
    return OK;
}

//5、双向链表插入
Status ListInsert_DuL(DuLinkList &L, int i, ElemType e)
{
    //在带头结点的双向链表L中第i个位置之前插入元素e
    DuLNode *p;
    if(!(p = GetElem_DuL(L, i)))
        return ERROR;
    DuLNode *s = new DuLNode;
    s->data = e;
    s->prior = p->prior;
    p->prior->next = s;
    s->next = p;
    p->prior = s;
    return OK;
}

//11、双向链表删除
Status ListDelete_DuL(DuLinkList &L, int i)
{
    //删除带头结点的双向链表L中的第i个元素
    DuLNode *p;
    if(!(p = GetElem_DuL(L, i)))
        return ERROR;
    p->prior->next = p->next;
    p->next->prior = p->prior;
    delete p;
    return OK;
}

int main()
{
    cout<<"------------------------双向链表菜单----------------------"<<'n';
    cout<<"操作0：退出程序"<<'n';
    cout<<"操作1：创建一个带头结点的双向链表，且遍历此链表"<<'n';
    cout<<"操作2：在双向链表中的第i个结点前插入一个结点值为e的正整数"<<'n';
    cout<<"操作3：删除双向链表链表中的第j个结点"<<'n';
    int a, n, flag = 1;
    while(flag)
    {
        cout<<'n'<<"请选择要执行的操作：";
        while(cin>>a)
        {
            if(a < 0 || a > 5)
                cout<<"请选择正确操作编号：";
            else
                break;
        }
        switch(a)
        {
        case 0:
        {
            cout<<"感谢使用本程序，祝您生活愉快！"<<'n';
            flag = 0;
            break;
        }
        case 1:
        {
            cout<<"----菜单-----"<<'n';
            cout<<"操作1：前插法"<<'n';
            cout<<"操作2：后插法"<<'n';
            cout<<"-------------"<<'n';
            cout<<"请选择单链表的创建方式：";
            int b;
            while(cin>>b)
            {
                if(b != 1 && b != 2)
                    cout<<"请选择正确操作编号：";
                else
                    break;
            }
            cout<<"请输入要建立的单链表的元素个数：";
            cin>>n;
            if(b == 1)
            {
                cout<<"请按逆位序依次输入这"<>i>>e;
            if(ListInsert_DuL(L, i, e))
            {
                cout<<"单链表插入完毕：";
                TraverseList_DuL(L);
            }
            else
                cout<<"i值不合法！"<<'n';
            break;
        }
        case 3:
        {
            int j;
            cout<<"删除单链表中的第j个结点，请输入j的值：";
            cin>>j;
            if(ListDelete_DuL(L, j))
            {
                cout<<"单链表删除完毕：";
                TraverseList_DuL(L);
            }
            else
                cout<<"j值不合法！"<<'n';
            break;
        }
        }
    }
    return 0;
}