数据结构与算法之—链表（二） 有序单链表合并

#include<iostream>
using namespace std;

struct node
{
	int element;
	node *next;
};


node *create_list(int n)
{
	if(n <= 0)
	{
		return  NULL;
	}
	
	node *head = NULL;
	node *p = new node;
	if(p == NULL)
	{
		return NULL;
	}
	head = p;
	while(--n)
	{
		node *q = new node;
		if(q == NULL)
		{
			return NULL;
		}
		p->next = q;
		p = q;
	}
	p->next = NULL;

	return head;
}

node *merg(node *head1, node* head2, node* &head)
{
	head = NULL;
	if(head1 == NULL && head2 == NULL)
		return NULL;

    node *p1 = head1;
	node *p2 = head2;
	node *t  = NULL;
	if(head1->element < head2->element)
	{
		head = t = head1;
		p1 = p1->next;
	}
	else
	{
		head = t = head2;
		p2 = p2->next;
	}

	while(p1 != NULL && p2 != NULL)
	{
		if(p1->element <= p2->element)
		{
			t->next = p1;
			t = p1;
			p1 = p1->next;
		}
		else
		{
			t->next = p2;
			t = p2;
			p2 = p2->next;
		}
	}

	t->next = p1 ? p1 : p2;

	return head;
	
}

int main()
{
	node *head1 = create_list(3);
	node *head2 = create_list(5);
	node *p1 = head1;
	node *p2 = head2;
	for(int i = 0; i < 3; i++)
	{
		p1->element = i + 3;
		cout<<p1->element<<' ';
		p1 = p1->next;
	}
	cout<<endl;
	for(int j = 0; j < 5; j++)
	{
		p2->element = j + 2;
		cout<<p2->element<<' ';
		p2 = p2->next;
	}	
	cout<<endl;

	node *head = NULL;
	head = merg(head1, head2, head);
	while(head != NULL)
	{
		cout<<head->element<<' ';
		head = head->next;
	}
	return  0;

}