将两个有序链表合并为一个新链表

#include <iostream>

#include <stdio.h>



typedef struct _Node

{

	int value;

	struct _Node *next;

}Node;



Node *MergeList(Node *listA, Node *listB);

void PrintList(Node *head);



int main()

{

	Node lista, nodea, listb, nodeb, nodec;

	lista.value = 2;

	nodea.value = 2;

	nodec.value = 19;

	lista.next = &nodea;

	nodea.next = &nodec;

	nodec.next = NULL;

	listb.value = 3;

	nodeb.value = 4;

	listb.next = &nodeb;

	nodeb.next = NULL;



	Node *listc = MergeList( &lista, &listb );

	PrintList(listc);

	system("pause");

	return 0;

}





/*

@brief merge two sorted lists to a new list which is sorted , too !



@param   in : listA 

@param   in : listB



@return  pHead  the new list of head

*/

Node *MergeList(Node *listA, Node *listB)

{

	Node *pHead = (Node *)malloc(sizeof(Node));

	if ( NULL == pHead )

	{

		printf("error, line %d malloc failed \n", __LINE__);

		return NULL;

	}

	pHead->next = NULL;



	Node *pNode = NULL;

	Node *pLink = pHead;



	// if the list head just is without data use 

	listA = NULL != listA ? listA->next : listA;

	listB = NULL != listB ? listB->next : listB;



	while( NULL != listA && NULL != listB )

	{

		pNode = (Node *)malloc(sizeof(Node));

		if ( NULL == pNode )

		{

			printf("error, line %d malloc failed \n", __LINE__);

			return pHead;

		}



		if ( listA->value <= listB->value )

		{

			pNode->value = listA->value;

			listA = listA->next;

		}

		else

		{

			pNode->value = listB->value;

			listB = listB->next;

		}

		pNode->next = NULL;

		pLink->next = pNode;

		pLink = pLink->next;

	}

			

	while ( NULL != listA )

	{

		pNode = (Node *)malloc(sizeof(Node));

		if ( NULL == pNode )

		{

			printf("error, line %d malloc failed \n", __LINE__);

			return pHead;

		}



		pNode->value = listA->value;

		listA = listA->next;

		pNode->next = NULL;

		pLink->next = pNode;

		pLink = pLink->next;

	}



	while ( NULL != listB )

	{

		pNode = (Node *)malloc(sizeof(Node));

		if ( NULL == pNode )

		{

			printf("error, line %d malloc failed \n", __LINE__);

			return pHead;

		}



		pNode->value = listB->value;

		listB = listB->next;

		pNode->next = NULL;

		pLink->next = pNode;

		pLink = pLink->next;

	}



	return pHead;

}



void PrintList(Node *head)

{

	if ( NULL == head )

	{

		printf("error, list is NULL\n");

		return ;

	}



	// if the list head just is without data use 

	head = head->next;



	while( NULL != head )

	{

		printf("%d\t", head->value);

		head = head->next;

	}

	printf("\n");

}