【面试题】链表合并-递归和非递归

#include <stdio.h>
#include <stdlib.h>
 
typedef struct _Node
{
	int data;
	_Node* next;
}Node, *LinkList;
 
bool CreateList(LinkList &head, const int *data, const int len) 
 {
	 Node *cur = NULL;
	 Node *next = NULL;
	 int i;
	 cur = (LinkList)malloc(sizeof(Node));
	 if(cur == NULL)
	 {
		 return false;
	 }
	 cur->data = data[0];
	 cur->next = NULL;
	 head = cur;
 
	for(i=1; i<len; i++)
	{
		next = (LinkList)malloc(sizeof(Node));
		if(next == NULL)
		{
			return false;
		}
		next->data = data[i];
		next->next = NULL;
		cur->next = next;
		cur = cur->next;
	} 
	return true;
}
 
void PrintList(LinkList head) 
{
	while(head != NULL)
	{
		printf(" %d", head->data);
		head = head->next;
	}
}
 
//一般合并
LinkList MergeList(LinkList head1, LinkList head2)
{
	if (head1 == NULL)
	{
		return head2;
	}
	if (head2 == NULL)
	{
		return head1;
	}
 
	LinkList head = NULL;
	LinkList p1 = NULL;
	LinkList p2 = NULL;
	if ( head1->data < head2->data )
	{
		head = head1;
		p1 = head1->next;
		p2 = head2;
	}
	else
	{
		head = head2;
		p2 = head2->next;
		p1 = head1;
	}
	LinkList cur = head;
	while ( (p1!=NULL) && (p2!=NULL) )
	{
		if ( p1->data <= p2->data )
		{
			cur->next = p1;
			cur = p1;
			p1 = p1->next;
		}
		else
		{
			cur->next = p2;
			cur = p2;
			p2 = p2->next;
		}
	}
 
	if(p1 != NULL )
	{
		cur->next = p1;
		if(p2 != NULL)
		{
			cur->next = p2;
		}
		return head;
	}
}
//递归合并
LinkList RMergeList(LinkList head1, LinkList head2)
{
	if(head1 == NULL)
	{
		return head2;
	}
	if(head2 == NULL)
	{
		return head1;
	} 
	LinkList head = NULL;
	if (head1->data < head2->data)
	{
		head = head1;
		head->next = RMergeList(head1->next, head2);
	}
	else
	{
		head = head2;
		head->next = RMergeList(head1, head2->next);
	}
	return head;
}
 
void main()
{
	 int data1[] = {1, 2, 3, 5};
	 int len1 = sizeof(data1)/sizeof(int);
	 int data2[] = {2, 4, 6};
	 int len2 = sizeof(data2)/sizeof(int);
 
	 LinkList head;
	 LinkList head1;
	 LinkList head2;
 
	if( !CreateList(head1, data1, len1) )
	 {
		 printf("创建链表失败！\n");
		 return;
	 }
 
	if( !CreateList(head2, data2, len2) )
	 {
		 printf("创建链表失败！\n");
		 return;
	 }
 
	printf("链表1：");
	PrintList(head1);
	printf("\n");
 
	printf("链表2：");
	PrintList(head2);
	printf("\n");
 
	head = MergeList(head1, head2);
	printf("一般合并：");
	PrintList(head);
	printf("\n");
 
	if( !CreateList(head1, data1, len1) )
	{
		printf("创建链表失败！\n");
		return;
	}
	if(!CreateList(head2, data2, len2) )
	{
		printf("创建链表失败！\n");
		return;
	}
 
	printf("链表1：");
	PrintList(head1);
	printf("\n");
 
	printf("链表2：");
	PrintList(head2);
	printf("\n");
 
	head = RMergeList(head1, head2);
	printf("递归合并：");
	PrintList(head);
	printf("\n");
}