单链表操作

单链表操作的实现，包括初始化，插入，删除，遍历，排序，归并等。为了方便，使用了带头结点的单链表。注意，单链表的局限之处在于只能向后继方向进行遍历，所以在进行插入和删除操作时要找到目标结点的前驱结点。这个比较关键。其他的细节就比较简单了。

代码如下：

// LinkList.cpp : 定义控制台应用程序的入口点。
//带头结点的单链表

#include "stdafx.h"
 
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <vector>

using namespace std;

typedef struct LNode {
	int data;
	LNode* next;
}LNode, *LinkList;

//取第i个位置的元素 
bool getElem(const LinkList& L, int pos, int& e)
{
	LNode* p = L;
	int j = 0;
	while (p&&j<pos - 1)
	{
		p = p->next;
		++j;
	}
	if (!p || j>pos - 1)
		return false;
	e = p->next->data;
	return true;
}

//插入元素 
bool insertList(LinkList& L, int pos, int e)
{
	LNode* p = L;
	int j = 0;

	//找到插入位置 
	while (p&&j<pos - 1)
	{
		p = p->next;
		++j;
	}
	if (!p || j>pos - 1) //插入位置大于表长或小于1 
		return false;

	LNode* temp = (LNode*)malloc(sizeof(LNode));
	temp->data = e;
	temp->next = p->next;
	p->next = temp;
	return true;
}

//删除元素并返回 
bool removeList(LinkList& L, int pos, int& e)
{
	LNode* p = L;
	int j = 0;
	//找到待删除元素的前驱 
	while (p&&j<pos - 1)
	{
		p = p->next;
		++j;
	}
	if (!p || j>pos - 1)
		return false;
	LNode* q = p->next;
	p->next = q->next;
	e = q->data;
	free(q);
	return true;
}

//逆序建立表 
void createList(LinkList& L)
{
	L = (LNode*)malloc(sizeof(LNode));
	L->next = NULL;
	int n;

	//逆序插入 
	while (cin >> n)
	{
		insertList(L, 1, n);
	}
}

void outputList(const LinkList& L)
{
	LNode* p = L;
	while (p->next)
	{
		p = p->next;
		cout << p->data << endl;
	}
	cout << endl;
}

void sortList(LinkList& L)
{
	vector<int> s;
	LNode* p = L;
	p = p->next;
	while (p)
	{
		s.push_back(p->data);
		p = p->next;
	}
	sort(s.rbegin(), s.rend());
	p = L;
	p = p->next;
	while (p && !s.empty())
	{
		p->data = s.back();
		s.pop_back();
		p = p->next;
	}
}

void mergeList(LinkList& La, LinkList& Lb, LinkList& Lc)
{
	LNode* pa = La->next;
	LNode* pb = Lb->next;
	Lc = La;
	LNode* pc = Lc;
	while (pa&&pb)
	{
		if (pa->data<pb->data)
		{
			pc->next = pa;
			pc = pa;
			pa = pa->next;
		}
		else
		{
			pc->next = pb;
			pc = pb;
			pb = pb->next;
		}
	}
	pc->next = pa ? pa : pb;
	free(Lb);
}

int main()
{
	LinkList L;
	createList(L);
	cout << "Init:\n";
	outputList(L);

	insertList(L, 3, 1000);
	cout << "Insert:\n";
	outputList(L);

	int e;
	removeList(L, 3, e);
	cout << "Remove:\n";
	outputList(L);

	sortList(L);
	cout << "Sort:\n";
	outputList(L);

	cout << "La:\n";
	for (int i = 1; i <= 5; i++)
	{
		getElem(L, i, e);
		cout << e << endl;
	}
	cout << endl;
	LinkList L2;
	LinkList L3;
	L2 = (LNode*)malloc(sizeof(LNode));
	L2->next = (LNode*)malloc(sizeof(LNode));
	L2->next->data = -10;
	L2->next->next = (LNode*)malloc(sizeof(LNode));
	L2->next->next->data = 22;
	L2->next->next->next = NULL;
	cout << "Lb:\n";
	for (int i = 1; i <= 2; i++)
	{
		getElem(L2, i, e);
		cout << e << endl;
	}
	cout << endl;
	mergeList(L, L2, L3);
	cout << "Merge:\n";
	outputList(L3);
	system("pause");
	return 0;
}