数据结构—单向链表

单向链表（单链表）是链表的一种，其特点是链表的链接方向是单向的，对链表的访问要通过顺序读取从头部开始；链表是使用指针进行构造的列表；又称为结点列表，因为链表是由一个个结点组装起来的；其中每个结点都有指针成员变量指向列表中的下一个结点。

相比较普通的线性结构：

（1）单个结点创建非常方便，普通的线性内存通常在创建的时候就需要设定数据的大小

（2）结点的删除非常方便，不需要像线性结构那样移动剩下的数据

（3）结点的访问方便，可以通过循环或者递归的方法访问到任意数据，但是平均的访问效率低于线性表

代码：

#define _CRT_SECURE_NO_WARNINGS
#include "iostream"
#include "string"
using namespace std;

typedef struct Person
{
	char name[32];
	int age;
}DATATYPE;

typedef struct Node
{
	DATATYPE data;
	Node *next;
}linkNode;

typedef struct List
{
	linkNode *head;
	int clen;
}linkList;

//链表初始化
linkList* initList()
{
	linkList* mlist = new linkList;
	if (NULL == mlist)
	{
		perror("list init");
		exit(1);
	}
	mlist->clen = 0;
	mlist->head = NULL;
	return mlist;
}

//头插
int insertHead(linkList* mlist,DATATYPE *mdata)
{
	linkNode* newnode = new linkNode;
	if (NULL == newnode)
	{
		perror("insertHead newnode");
		return 1;
	}
	newnode->data = *mdata;
	newnode->next = NULL;

	newnode->next = mlist->head;
	mlist->head = newnode;
	mlist->clen++;
	return 0;
}

//尾插
int insertTail(linkList *mlist, DATATYPE *mdata)
{
	linkNode* newnode = new linkNode;
	if (NULL == newnode)
	{
		perror("insertTail newnode");
		return 1;
	}
	newnode->data = *mdata;
	newnode->next = NULL;
	
	if (NULL == mlist->head)
	{
		mlist->head = newnode;
	}
	else
	{
		linkNode* tmp = mlist->head;
		while (tmp->next)
		{
			tmp = tmp->next;
		}
		tmp->next = newnode;
	}

	mlist->clen++;
	return 0;
}

//删除指定数据
int delList(linkList *mlist, char *pname)
{
	if (NULL == mlist->head)			//判断链表是否为空
	{
		cout << "链表已为空" << endl;
		return 1;
	}
	if (NULL == mlist->head->next)   
	{
		if (0 == strcmp(mlist->head->data.name,pname))   //若只有表头，且表头数据为要删除的数据，则删除表头
		{
			delete mlist->head;
			mlist->head = NULL;
			return 0;
		}
		else
		{
			cout << "该数据不存在" << endl;
			return 1;
		}
	}
	else
	{
		linkNode *p = mlist->head;
		linkNode *q = mlist->head;
		while (p)
		{
			if (0 == strcmp(p->data.name,pname))			//查看第一个结点是不是要删除的数据
			{
				if (p == q)
				{
					mlist->head = p->next;
				}
				else
				{
					q->next = p->next;
				}
				delete p;
				mlist->clen--;
				return 0;
			}
			else
			{
				q = p;
				p = p->next;
			}
		}
	}
	cout << "未找到要删除的元素" << endl;
	return 1;
}

//删除链表
int destoryList(linkList *mlist)
{
	linkNode *tmp;

	while (mlist->head)
	{
		tmp = mlist->head;
		mlist->head = tmp->next;
		delete tmp;
		tmp = NULL;
	}
	delete mlist;
	mlist = NULL;
	cout << "释放完成" << endl;
	return 0;
}

//查找
linkNode* findList(linkList *mlist, char* pname)
{
	linkNode *tmp = mlist->head;
	while (tmp)
	{
		if (0 == strcmp(tmp->data.name,pname))
		{
			return tmp;
		}
		tmp = tmp->next;
	}
	cout << "此人不在链表中。。。" << endl;
	return NULL;
}

//链表逆序
int reverseList(linkList *mlist)
{
	linkNode *p = mlist->head->next;
	linkNode *q = mlist->head;
	while (p)						//头插法
	{
		q->next = p->next;
		p->next = mlist->head;
		mlist->head = p;
		p = q->next;
	}

	return 0;
}

//链表排序
int sortList(linkList *mlist)
{
	if (NULL == mlist->head)
	{
		cout << "链表为空" << endl;
	}
	if (NULL == mlist->head->next)
	{
		cout << "链表只有一个表头" << endl;
	}
	else
	{
		linkNode *p, *q, tmp;
		q = mlist->head;
		while (q->next != NULL)
		{
			p = q->next;
			while (p != NULL)
			{
				if (p->data.age < q->data.age)
				{
					tmp.data = p->data;
					p->data = q->data;
					q->data = tmp.data;
				}
				p = p->next;
			}
			q = q->next;
		}	
	}
	return 0;
}

//修改链表元素
int updataList(linkList *mlist,char *oldname,char *newname)
{
	linkNode *tmp;
	tmp = findList(mlist, oldname);
	strcpy(tmp->data.name, newname);
	return 0;
}


//打印链表
int showList(linkList* mlist)
{
	linkNode *tmp = mlist->head;
	while(tmp)
	{
		cout << "名字:" << tmp->data.name << " " << "年龄:" << tmp->data.age << endl;
		tmp = tmp->next;
	}
	return 0;
}

int main()
{
	linkList *m_list = initList();
	DATATYPE data1 = { "张三",15 };	
	DATATYPE data4 = { "王麻子",50 };

	insertTail(m_list, &data4);
	insertHead(m_list, &data1);
	showList(m_list);

	cout << "--------------------------------------------" << endl;
	cout << "头插：" << endl;
	DATATYPE data2[2] = {
		{"李四",16},
		{"王五",17}
	};
	insertHead(m_list, &data2[0]);
	insertHead(m_list, &data2[1]);
	cout << "当前链表长度：" << m_list->clen << endl;
	showList(m_list);

	cout << "--------------------------------------------" << endl;
	cout << "尾插:" << endl;
	DATATYPE data3[4] = {
		{ "东邪", 20 },
		{ "西毒", 21 },
		{ "南帝", 22 },
		{ "北丐", 23 },
	};
	insertTail(m_list, &data3[0]);
	insertTail(m_list, &data3[1]);
	insertTail(m_list, &data3[2]);
	insertTail(m_list, &data3[3]);
	cout << "链表排序：" << endl;
	sortList(m_list);
	cout << "当前链表长度：" << m_list->clen << endl;
	showList(m_list);
	cout << "--------------------------------------------" << endl;
	cout << "查找:" ;
	linkNode *res = findList(m_list, "张三");

	if (res != NULL)
	{
		cout << "查到此人：" << res->data.name << " " << "此人年龄：" << res->data.age << endl;
	}

	cout << "--------------------------------------------" << endl;
	cout << "修改链表元素:";
	updataList(m_list, "李四", "赵六");
	
	cout << "--------------------------------------------" << endl; 
	cout << "指定删除：" << "王麻子" << endl;
	delList(m_list, "王麻子");

	cout << "当前链表长度：" << m_list->clen << endl;
	showList(m_list);
	
	cout << "--------------------------------------------" << endl;
	cout << "链表逆序：" << endl;
	reverseList(m_list);
	cout << "当前链表长度：" << m_list->clen << endl;
	showList(m_list);
	
	destoryList(m_list);
	system("pause");	
	return 0;
}