求兩個單鏈表是否相交（包括環的問題）

單鏈表操作之（判斷是否帶環，求環長，求入口節點）點擊打開鏈接

#define _CRT_SECURE_NO_WARNINGS 1
typedef int DataType;
#define NULL 0
#include<stdio.h>
#include<windows.h>
#include<assert.h>
typedef struct Node
{
	DataType data;
	struct Node*next;
}Node, *LinkList;
void InitList(LinkList *L)
{
	*L = (Node*)malloc(sizeof(Node));
	if (*L == NULL){
		printf("申請內存空間失敗");
	}
	(*L)->next = NULL;
}
LinkList BuyNode(DataType data)
{
	LinkList NewNode = NULL;
	NewNode = (LinkList)malloc(sizeof(Node));
	if (NewNode == NULL){
		printf("爲節點創建空間失敗");
	}
	NewNode->data = data;
	NewNode->next = NULL;
	return NewNode;
}
void PrintList(LinkList L)
{
	LinkList Cur = L;
	if (L == NULL){
		printf("NULL");

	}
	Cur = Cur->next;
	while (Cur)
	{
		if (Cur == NULL)
			return;
		printf("%d--->", Cur->data);
		Cur = Cur->next;
	}
	printf("NULL\n");
}
void PushBack(LinkList* L, DataType data)
{
	assert(L);
	LinkList Cur = *L;
	if (Cur == NULL){
		Cur = BuyNode(data);
	}
	while (Cur->next)
	{
		Cur = Cur->next;
	}
	Cur->next = BuyNode(data);
}
int Size(LinkList L){
	assert(L);
	LinkList Cur = L;
	int count = 0;
	if (Cur->next == NULL)
		return 1;
	while (Cur->next){
		Cur = Cur->next;
		count++;
	}
	return count;
}
LinkList Find(LinkList L, DataType data)
{
	assert(L);
	if (L == NULL){
		return NULL;
	}
	LinkList Cur = L;
	while (Cur != NULL)
	{
		if (Cur->data == data){
			return Cur;
		}
		Cur = Cur->next;
	}
	return NULL;
}
LinkList HasCircle(LinkList L)
{
	LinkList Fast = L;
	LinkList Slow = L;
	while (Fast&&Fast->next){
		Fast = Fast->next->next;
		Slow = Slow->next;
		if (Slow == Fast)
			return Slow;
	}
	return NULL;
}
//判斷不帶環的鏈表是否相交兩種情況Y，V尾節點相同
int IsCrossNodeWithoutCircle1(LinkList L1, LinkList L2)
{
	LinkList PL1=L1;
	LinkList PL2=L2;

	if (L1 == NULL || L2 == NULL)
		return 0;
	while(PL1->next)
	{
		PL1 = PL1->next;

	}
	while(PL2->next){
		PL2 = PL2->next;
	}
	if (PL1==PL2)
		return 1;
	else
		return 0;
}
//判斷不帶環的鏈表是否相交兩種情況Y，用L1的尾節點連接L2的頭節點如果L1帶環則L1與l2相交
int IsCrossNodeWithoutCircle2(LinkList L1, LinkList L2)
{
	LinkList PL1 = L1;
	LinkList PL2 = L2;

	if (L1 == NULL || L2 == NULL)
		return 0;
	while (PL1->next)
	{
		PL1 = PL1->next;
	}
	PL1->next = PL2;
	if (NULL!=HasCircle(L1))
		return 1;
	else
		return 0;
}
test5()
{
	LinkList L = NULL;
	LinkList M = NULL;
	LinkList S = NULL;
	InitList(&L);
	InitList(&M);
	PushBack(&L, 1);
	PushBack(&L, 2);
	PushBack(&L, 4);
	PushBack(&M, 5);
	PushBack(&M, 6);
	S = Find(M, 6);
	S->next = Find(L, 2);
	printf("%d %d", IsCrossNodeWithoutCircle1(L, M), Size(L));
}
//求相交節點。。。先讓長的鏈表遍歷L1-L2，再讓連個鏈表一起遍歷當L1=L2時L1和L2都是相交節點
LinkList GetCrossNodeWithoutCircle(LinkList L1, LinkList L2)
{
	if (0 == IsCrossNodeWithoutCircle1(L1, L2))
		return NULL;
	int size1 = Size(L1);
	int size2 = Size(L2);
	LinkList PL1 = L1;
	LinkList PL2 = L2;
	int gap = size1 - size2;
	if (gap > 0){
		while (gap--){
			PL1 = PL1->next;
		}
	}
	else
	{
		while (gap++){
			PL2 = PL2->next;
		}
	}
	while (PL1!=PL2){

		PL1 = PL1->next;
		PL2 = PL2->next;
	}
	return PL1;
}
//PL1       PL2   0---》代表不帶環，1--》代表帶環
//0         0  倆不帶環單鏈表相交
//0         1  不存在
//1         0  不存在
//1         1  環內相交，環外相交
int IsCrossWithCircle(LinkList L1,LinkList L2)  //1代表倆無環單鏈表相交，2代表倆有環單鏈表相交
{
	LinkList MeetNode1 = HasCircle(L1);
	LinkList MeetNode2 = HasCircle(L2);
	if (NULL == MeetNode1 || NULL == MeetNode2)
	{
		if (IsCrossNodeWithoutCircle2(L1, L2)!= NULL)
			return 1;
	}
	else if (MeetNode1&&MeetNode2)
	{
		LinkList Cur = MeetNode1;
		while (Cur->next != MeetNode1){
			if (Cur == MeetNode2)
				return 2;
			Cur = Cur->next;
		}
		if (Cur == MeetNode2)
			return 2;
	}
}
test6()
{
	LinkList L = NULL;
	LinkList M = NULL;
	LinkList S = NULL;
	InitList(&L);
	InitList(&M);
	PushBack(&L, 1);
	PushBack(&L, 2);
	PushBack(&L, 4);
	PushBack(&M, 5);
	PushBack(&M, 6);
	S = Find(M, 6);
	S->next = Find(L, 2);
	printf("%d", IsCrossNodeWithoutCircle2(L, M));
}
test7()
{
	LinkList L = NULL;
	LinkList M = NULL;
	LinkList S = NULL;
	InitList(&L);
	InitList(&M);
	PushBack(&L, 1);
	PushBack(&L, 2);
	PushBack(&L, 4);
	PushBack(&M, 5);
	PushBack(&M, 6);
	S = Find(M, 6);
	S->next = Find(L, 2);
	LinkList Q=GetCrossNodeWithoutCircle(L, M);
	printf("%d", Q->data);
}
test8()
{
	LinkList L = NULL;
	LinkList M = NULL;
	LinkList S = NULL;
	InitList(&L);
	InitList(&M);
	PushBack(&L, 1);
	PushBack(&L, 2);
	PushBack(&L, 3);
	PushBack(&L, 4);
	PushBack(&L, 5);
	S = Find(L, 5);
	S->next = Find(L, 3);
	PushBack(&M, 6);
	PushBack(&M, 7);
	S = Find(M, 7);
	S->next = Find(L, 3);
	printf("%d", IsCrossWithCircle(L,M));
}
int main()
{
	test8();
	//test7();
	//test6();
	//test5();
	//test4();
	//test3();
	system("pause");
	return 0;
}