链表的基本操作-双向链表

/*
链表的基本操作~~
开发环境：vs2010
win32 console application.
*/

#include "stdafx.h"

#include <iostream>

using namespace std;

struct node
{
	int data;
	node * next;  // 指向后续节点
	node * pre;   // 指向前驱节点
};
node * createBidirList (int n);
void outputBidirList(node * head);
node * insertData(int n, node * head);
node * deleteData(int n, node * head);

int main() {
    int n;
	node * listHead = NULL;
	cout << "Please enter the number of nodes: ";
	cin >> n;  // 可以输入5 (1 2 3 4 5)
	if(n > 0)
		listHead = createBidirList(n);
	outputBidirList(listHead);
	insertData(7, listHead);
	outputBidirList(listHead);
	insertData(6, listHead);
	deleteData(2, listHead);
	outputBidirList(listHead);
	return 0;
}

//  按数据输入的顺序建立双向链表 
node * createBidirList (int n) {
	node * temp, *tail = NULL, *head = NULL;
	int num;
	cin >> num;
	head = new node; //为新节点动态分配内存
	if(head == NULL) {
		cout << "No memory available!";
		return NULL;
	}
	else  {
		head->data = num;
		head->next = NULL;
		head->pre = NULL;
		tail = head;
	}

	for(int i = 0; i < n - 1; i++) {
		cin >> num;
		temp = new node;  //为新节点动态分配内存
		if(temp == NULL) {
			cout << "No memory availabe";
			return head;
		}
		else {
			temp->data = num;
			temp->next = NULL;
			temp->pre = tail;
			tail->next = temp;
			tail = temp;
		}
	}
	return head;
}

// 输出双向链表中各节点的data成员的值 
void outputBidirList(node * head) {
	cout << "List: ";
	node * curNode = head;
	while(curNode) {
		if(curNode->pre)
			cout << " <- ";
		cout << curNode->data;
		if(curNode->next)
			cout << " -> ";
		curNode = curNode->next;
	}
	cout << endl;
	return;
}

// 将整数n插入到一个已排序的双向链表中(从小到大)
node * insertData(int n, node * head) {
	node * curNode = head;  // 指向插入点的后节点
	node * preNode = NULL;  // 指向插入点的前节点
	node * newNode = NULL;  // 指向新建节点
	// 寻找插入位置
	while((curNode != NULL) && (curNode->data < n)) {
		preNode = curNode;
		curNode = curNode->next;
	}
	newNode = new node;  // 为新节点动态分配内存
	if(newNode == NULL) { // 内存分配不成功
		cout << "Not memory available!";
		return head;
	}
	newNode->data = n;
	if(preNode == NULL) { // 链头
		newNode->next = curNode;
		newNode->pre = NULL;
		if(curNode != NULL)
			curNode->pre = newNode;
		head = newNode; return head;
	}
	if(curNode == NULL) {  // 链尾
		newNode->pre = preNode;
		preNode->next = newNode;
		newNode->next = NULL;
		return head;
	}
	else
	{ // 链中
		preNode->next = newNode;
		newNode->next = curNode;
		newNode->pre = preNode;
		curNode->pre = newNode;
		return head;
	}
}

// 在双向链表中查找并删除指定
node * deleteData(int n, node * head) {
	 node * curNode = head; // 指向当前节点
	 while(curNode && curNode->data != n)
		 curNode = curNode->next;
	 if(curNode == NULL) {
		 cout << "Can't find " << n << endl;
		 return head;
	 }
	 if(curNode->pre == NULL) {
		 head = head->next;
		 head->pre = NULL;
	 }
	 else {
		 curNode->pre->next = curNode->next;
		 if(curNode->next != NULL)
			 curNode->next->pre = curNode->pre;
	 }
	 delete curNode;
	 return head; // 返回链首指针
}