单向链表

#include<stdio.h>
#include<stdlib.h>
typedef struct _ListNode{
	int m_nKey;
	struct _ListNode *m_pNext;
}ListNode;
//插入节点
void InsertNode(ListNode **plistHead, int val)
{
	ListNode *node = (ListNode*)malloc(sizeof(ListNode));
	node->m_nKey = val;
	node->m_pNext = NULL;
	if (*plistHead == NULL){
		*plistHead = node;
		return;
	}
	ListNode *tmp = *plistHead;
	while (tmp->m_pNext) tmp = tmp->m_pNext;
	tmp->m_pNext = node;
}
//查找指定元素
ListNode* FindNode(ListNode* pListHead, int val)
{
	while (pListHead){
		if (pListHead->m_nKey == val) return pListHead;
		pListHead = pListHead->m_pNext;
	}
	return NULL;
}
//O(1)时间内删除指定节点
void DeleteNode(ListNode* pListHead, ListNode* pToBeDeleted)
{
	ListNode* tmp;
	if (pToBeDeleted->m_pNext){
		tmp = pToBeDeleted->m_pNext;
		pToBeDeleted->m_nKey = pToBeDeleted->m_pNext->m_nKey;
		pToBeDeleted->m_pNext = pToBeDeleted->m_pNext->m_pNext;
		free(tmp);
		return;
	}
	tmp = pListHead;
	while (pListHead->m_pNext){
		tmp = pListHead;
		pListHead = pListHead->m_pNext;
	}
	tmp->m_pNext = NULL;
	free(pListHead);
}
//打印链表
void PrintList(ListNode* pListHead)
{
	while (pListHead){
		printf("%d\t", pListHead->m_nKey);
		pListHead = pListHead->m_pNext;
	}
}
//从尾到头输出链表,递归
void ReversePrintList(ListNode* pListHead)
{
	if (pListHead->m_pNext) ReversePrintList(pListHead->m_pNext);
	printf("%d\t", pListHead->m_nKey);
}
//返回链表倒数第K个元素,倒数第0个为尾节点
ListNode* lastK(ListNode* head, int k)
{
	if (k < 0) return NULL;
	if (head == NULL) return NULL;
	ListNode *pk = head, *p = head;
	while (k-- > 0){
		if (pk->m_pNext) pk = pk->m_pNext;
		else return NULL;
	}
	while (pk->m_pNext){
		p = p->m_pNext;
		pk = pk->m_pNext;
	}
	return p;
}
//反转链表
void reverseList(ListNode** head)
{
	ListNode* p = *head;
	while (p&&p->m_pNext){
		ListNode *tmp = p->m_pNext;
		p->m_pNext = tmp->m_pNext;
		tmp->m_pNext = *head;
		*head = tmp;
	}
}
//将链表内容存于数组，再逆序输出
void ReversePrintList2(ListNode* pListHead)
{
	int len = 0;
	ListNode* p = pListHead;
	while (p){
		++len;
		p = p->m_pNext;
	}
	int *r = (int*)malloc(len*sizeof(int));
	p = pListHead;
	for (int i = 0; i < len; ++i){
		r[i] = p->m_nKey;
		p = p->m_pNext;
	}
	for (int i = 0; i < len; ++i)
		printf("%d\t", r[len - i - 1]);
}
//判断两个单向链表是否相交，单向链表相交，只能相交与尾节点
int isJoinedSimple(ListNode* head1, ListNode* head2)
{
	if (head1 == NULL || head2 == NULL) return 0;
	while (head1->m_pNext) head1 = head1->m_pNext;
	while (head2->m_pNext) head2 = head2->m_pNext;
	return head1 == head2;
}
//判断链表是否有环，若有，返回碰撞点（追赶法，一次1步，一次2步）
ListNode* testCycle(ListNode* head)
{
	ListNode *p1, *p2;
	p1 = p2 = head;
	while (p2&&p2->m_pNext){
		p1 = p1->m_pNext;
		p2 = p2->m_pNext->m_pNext;
		if (p1 == p2) return p1;
	}
	return NULL;
}
int isJoinedList(ListNode* head1, ListNode* head2)
{
	ListNode* cyc1 = testCycle(head1);
	ListNode* cyc2 = testCycle(head2);
	if (cyc1 == NULL&&cyc2 == NULL) return isJoinedSimple(head1, head2);
	if (cyc1 == NULL&&cyc2 || cyc1&&cyc2 == NULL) return 0;
	ListNode* p = cyc1;
	while (1){
		if (p == cyc2 || p->m_pNext == cyc2) return 1;
		p = p->m_pNext->m_pNext;
		if (p == cyc1 || p->m_pNext == cyc1) return 0;
	}

}
//合并两个非降序链表
ListNode* mergeList(ListNode* head1, ListNode* head2)
{
	if (head1==NULL) return head2;
	if (head2==NULL) return head1;
	ListNode* head;
	if (head1->m_nKey < head2->m_nKey){
		head = head1;
		head1 = head1->m_pNext;
	}
	else{
		head = head2;
		head2 = head2->m_pNext;
	}
	ListNode *p = head;
	while (head1&&head2)
	{
		if (head1->m_nKey < head2->m_nKey){
			p->m_pNext = head1;
			p = head1;
			head1=head1->m_pNext;
		}
		else if (head1->m_nKey > head2->m_nKey){
			p->m_pNext = head2;
			p = head2;
			head2 = head2->m_pNext;
		}
		else{
			p->m_pNext = head1;
			p = head1;
			head1 = head1->m_pNext;
			head2 = head2->m_pNext;
		}
		//break;
	}
	p->m_pNext = (head1 == NULL) ? head2 : head1;
	return head;
}

int main()
{
	ListNode *head = NULL;
	int a[] = { 3, 7, 5, 2, 6, 3, 2,8 };
	for (int i = 0; i < 8;++i)
		InsertNode(&head,a[i]);
	PrintList(head);
	printf("\n");
	ReversePrintList2(head);
	printf("\n");
	ListNode* tmp = FindNode(head, 2);
	//if (tmp) printf("%d\n", tmp->m_nKey);
	DeleteNode(head, tmp);
	PrintList(head);
	printf("\n");

	reverseList(&head);
	PrintList(head);
	printf("\n");

	ListNode* pk = lastK(head, 3);
	if (pk) printf("%d\n", pk->m_nKey);

	ListNode *head2, *head3, *head4, *head5;
	head2 = head3 = head4 = head5 = NULL;
	int x[] = { 3, 7, 9, 2, 1, 0, 4, 32, 76, 54 };
	for (int i = 0; i < 10; ++i)
		InsertNode(&head2,x[i]);
	if (isJoinedList(head, head2))
		printf("head and head2 joinedSimple YES\n");
	else printf("head and head2 joinedSimple NO\n");
	ListNode* p = (ListNode*)malloc(sizeof(ListNode));
	p->m_nKey = 1000;
	p->m_pNext = NULL;
	ListNode *ph, *ph2;
	ph = head; ph2 = head2;
	while (ph->m_pNext) ph = ph->m_pNext;
	while (ph2->m_pNext) ph2 = ph2->m_pNext;
	ph->m_pNext = ph2->m_pNext = p;
	ph = ph->m_pNext; ph2 = ph2->m_pNext;
	if (isJoinedList(head, head2))
		printf("head and head2 joinedSimple YES\n");
	else printf("head and head2 joinedSimple NO\n");
	
	int y[] = { 3, 7, 9, 2, 1, 0, 4, 32, 76, 54 };
	for (int i = 0; i < 10; ++i)
		InsertNode(&head3, y[i]);
	ListNode* ph3 = head3;
	while (ph3->m_pNext) ph3 = ph3->m_pNext;
	ListNode* pnode = FindNode(head3, 0);
	ph3->m_pNext = pnode;
	if (testCycle(head3)) printf("head3 has cycle\n");
	if (isJoinedList(head, head3))
		printf("head and head3 joined YES\n");
	else printf("head and head3 joined NO\n");
	pnode = FindNode(head2, 0);
	ph2->m_pNext = pnode;
	if (testCycle(head2)) printf("head2 has cycle\n");
	if (isJoinedList(head2, head3))
		printf("head2 and head3 joined YES\n");
	else printf("head2 and head3 joined NO\n");
	head4 = pnode->m_pNext;
	if (isJoinedList(head2, head4))
		printf("head2 and head4 joined YES\n");
	else printf("head2 and head4 joined NO\n");
	if (isJoinedList(head3, head4))
		printf("head3 and head4 joined YES\n");
	else printf("head3 and head4 joined NO\n");
	
	int m1[] = { 1, 2, 3, 6 };
	int m2[] = { 2, 3, 5, 7 };
	ListNode *mhead1=NULL, *mhead2=NULL;
	for (int i = 0; i < 4; ++i)
		InsertNode(&mhead1, m1[i]);
	for (int i = 0; i < 4; ++i)
		InsertNode(&mhead2, m2[i]);
	ListNode* mhead = mergeList(mhead1, mhead2);
	PrintList(mhead);
	printf("\n");
}