双向链表

// list.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
using namespace std;
typedef struct list_node {
	int data;
	list_node *left;
	list_node *right;
} Node;
Node *create_node(int data)
{
	Node *node = new Node();
	node->data = data;
	node->left = node->right = NULL;
	return node;
}
void delete_node( Node * p )
{
	delete p;
	p = NULL ;
}
void insert_tail(Node *root , int data)
{
	Node *node = create_node( data );
	
	Node *last_node = root;
	while(last_node->right != NULL) last_node = last_node->right;
	last_node->right = node;
	node->left = last_node;
}
Node *find_node(Node *root , int data )
{
	Node *node = root ;
	while(node != NULL) {
		if( data == node->data ) {
			return node;
		}
		node = node->right;
	}
	return NULL;
}
void insert_back_node(Node *root, int dat , int data )
{
	Node *node = find_node(root,dat);
	if( node == NULL || node->left == NULL ) return;
	Node *new_node = create_node( data );
	node->left->right = new_node;
	new_node->right = node;
}
void insert_front_node(Node *root, int dat , int data )
{
	Node *node = find_node(root,dat);
	if( node == NULL ) return;	
	Node *new_node = create_node( data );
	new_node->right = node->right;
	new_node->left = node;	
	node->right = new_node;
}
void remote_node ( Node *root,int data )
{
	Node *node = find_node ( root , data );
	if( node == NULL ) {
		return ;
	} else if ( node->left == NULL ) {
		node->right->left = NULL;
	} else if ( node->right == NULL ) {
		node->left->right = NULL ;
	} else {
		node->left->right = node->right;
		node->right->left = node->left;
	}
	delete_node( node );
}
void traversal( Node *root )
{
	Node *last_node = root;
	do{
		cout<<last_node->data<<endl ;
		last_node = last_node->right;
	} while(last_node != NULL ) ;
}
int main(int argc, char* argv[])
{
	Node *root = create_node(1);
	insert_tail(root,4);
	insert_tail(root,5);
	insert_tail(root,800);
	insert_tail(root,6);
	insert_tail(root,7);
	Node *p = find_node(root,5);
	cout << p <<endl;
	if(p!=NULL) cout<<p->data <<endl;
	insert_back_node(root,5,20);
	insert_front_node(root,1,30);
	remote_node ( root , 6 ) ;
	traversal( root );
	return 0;
}