单链表经典实现

#include "stdafx.h"
#include 
#include 
#include 

typedef struct Node
{
	int data;
	struct Node *next;
} Node, *LinkedList;

//头插入法
LinkedList createH(int arr[])
{
	//int arr[5] = {2, 4, 6, 1, 3};

	LinkedList L;
	L = (LinkedList) malloc(sizeof(Node));
	L->next = NULL;

	int i = 0;
	while (i < 5)
	{
		LinkedList p;
		p = (LinkedList) malloc(sizeof(Node));
		p->data = arr[i];
		p->next = L->next;
		L->next = p;
		i++;
	}

	return L;
}

//尾插入法
LinkedList createT(int arr[])
{
	LinkedList L;
	L = (LinkedList) malloc(sizeof(Node));
	L->next = NULL;

	Node *t;
	t = L;

	int i = 0;
	while (i < 5)
	{
		LinkedList p;
		p = (LinkedList) malloc(sizeof(Node));
		p->data = arr[i];
		t->next = p;
		t = p;
		i++;
	}
	t->next = NULL;

	return L;
}


//打印循环链表
LinkedList createCircle(int arr[])
{
	LinkedList L;
	L = (LinkedList) malloc(sizeof(Node));
	L->next = NULL;

	Node *t;
	t = L;

	int i = 0;
	while (i < 5)
	{
		LinkedList p;
		p = (LinkedList) malloc(sizeof(Node));
		p->data = arr[i];
		t->next = p;
		t = p;
		i++;
	}
	t->next = L->next;

	return L;
}

LinkedList insert(LinkedList L, int point, int x)
{
	Node *p = L;
	int i;
	for (i = 1; i < point; i++)
	{
		p = p->next;
	}
	Node *tmp = (LinkedList) malloc(sizeof(Node));
	tmp->data = x;
	tmp->next = p->next;
	p->next = tmp;

	return L;
}

LinkedList deldata(LinkedList L, int x)
{
	Node *p = L;
	Node *pre = L;
	while (p->next)
	{
		if (p->data == x)
		{
			pre->next = p->next;
			free(p);
			break;
		}
		pre = p;
		p = p->next;
	}

	return L;
}

void print(LinkedList L)
{
	LinkedList p = L->next;

	while (p)
	{
		printf("%d ", p->data);
		p = p->next;
	}
	printf("\n");
}

//测试循环链表
void printClircleTest(LinkedList L)
{
	LinkedList p = L->next;

	int i = 0;
	while (p && i < 8)
	{
		printf("%d ", p->data);
		p = p->next;
		i++;
	}
	printf("\n");
}

//约瑟夫问题：m个人围城一圈，每间隔n则退出
void joseph(LinkedList L,int m, int n)
{
	int i = 0;
	int count = 0;
	Node *p = L->next;
	Node *pre = L->next;
	while (p && count < m)
	{
		if (i == n)
		{
			printf("%d ", p->data);
			pre->next = p->next;
			free(p);
			i = 0;
			count++;
			p = pre->next;
			continue;
		}
		pre = p;
		p = p->next;
		i++;
	}
	printf("\n");
}

//链表反转
LinkedList reverse(LinkedList list)
{
	Node	*tmp = NULL;
	Node	*p = NULL;

	if (list == NULL)
	{
		return NULL;
	}
	tmp = list->next;
	while (tmp->next != NULL)
	{
		p = tmp->next;
		tmp->next = p->next;
		p->next = list->next;
		list->next = p;
	}
	return list;
}

//2个有序单链表合并,有问题
LinkedList mergeTwoSortList(LinkedList L1, LinkedList L2)
{
	LinkedList p1 = L1->next;
	LinkedList p2 = L2->next;
	LinkedList tmp2 = L2->next;

	while (p1->next && p2->next)
	{
		if (p2->data > p1->data && p2->data <= p1->next->data)
		{
			tmp2 = p2->next;
			p2->next = p1->next;
			p1->next = p2;
			p2 = tmp2;
		}
		else
		{
			p2->next = p1;
			L1 = p2;
		}

		if (!p1 && p2) //链表1遍历完，直接在尾巴接上链表2
		{
			p1->next = p2;
			break;
		}

		if (p1 && !p2) //链表2遍历完，直接结束
		{
			break;
		}

		p1 = p1->next;	
	}

	return L1;
}

//合并两个有序链表
Node *Merge(Node *head1,Node *head2)
{
    Node *p1 = NULL;
    Node *p2 = NULL;
    Node *head = NULL;

    //找出两个链表中第一个结点较小的结点，head记录较小结点的头结点
    if(head1->next->data < head2->next->data)
    {
        head = head1;
        p1 = head1->next;
        p2 = head2->next;
    }
    else
    {
        head = head2;
        p2 = head2->next;
        p1 = head1->next;
    }

    Node *pcur = head;

    //在两个链表中遍历比较，将值较小的结点链接到pcur结点后
    while(p1 != NULL && p2 != NULL)
    {
        if(p1->data <= p2->data)
        {
            pcur->next = p1;
            pcur = p1;
            p1 = p1->next;
        }
        else
        {
            pcur->next = p2;
            pcur = p2;
            p2 = p2->next;
        }
    }
    //将p1或p2剩余的结点链到pcur之后，完成整个合并的过程
    if(p1 != NULL)
        pcur->next = p1;
    if(p2 != NULL)
        pcur->next = p2;
    
    return head;
}

//插入排序
void InsertionSort(LinkedList L)
{
	LinkedList p, point, pre; /*point用来指向需要插入的结点，pre用来指向point的前一个结点*/
	for(pre = L, point = L->next; point != NULL;)
	{
		p = L; /*p用来遍历寻找合适的插入位置*/
		for(;p != point; p = p->next)
		{
			if(p->next->data > point->data)/*如果找到，即把point所指向的结点插到p后面，然后跳出循环*/
			{
				pre->next = point->next;
				point->next = p->next;
				p->next = point;
				point = pre->next;
				break; /*别忘了此处的break*/
			}
		}

		if(p == point)/*此处需要注意，只在point所指结点不需要前插时，移动point和pre*/
		{
			point = point->next;
			pre = pre->next;
		}
	}
}

/*
判断两个链表是否相交：思路：如果两个链表相交了，那么交点肯定在最后一个结点，因此问题转化为求链表最后一个结点。
各自求显得麻烦，可以先判断链表的长度，len1 和 len2，长的链表先走 | len1 - len2 |步，然后开始同时走。
*/
int length_list(Node* head)
{
    int count=0;
    Node* current_node = head;
    if(current_node==NULL)
        return 0;
    else if(current_node->next==NULL)
        return 1;
    else{
        while(current_node->next!=NULL){
            count++;
            current_node = current_node->next;
        }
    }
    return count;
}

void intersection_twoLists(Node* head1,Node* head2)
{
    if(head1==NULL || head2==NULL)
    return;
    else{
        int length1 = length_list(head1);
        int length2 = length_list(head2);
        int step;
        if(length1 >= length2){
            step = length1 - length2;
            for(int i=1;i<=step;i++){
                head1 = head1->next;
            }
        }else{
            step = length2 - length1;
            for(int i=1;i<=step;i++){
                head2 = head2->next;
            }
        }
        while(head1->next!=NULL && head2->next!=NULL){
            head1 = head1->next;
            head2 = head2->next;
        }
        if(head1 == head2){
            printf("yes");
        }else{
            printf("no");
        }
    }
}

/*1.判断链表是否有环。如果没有，快走的链表则先遍历完。如果有，一个走1步，一个走2步，最终会相遇。
  2.环的长度：从碰撞点开始，再次碰撞则走过的路程就是环的长度。
  3.连接点位置：分别从碰撞点、头指针开始走，相遇的那个点就是连接点。
  4.链表长度：链表头到连接点+环的长度。
*/
bool hasLoop_list(Node* head)
{
    bool loop = false;
    Node* p1 = head;
    Node* p2 = head;
    if(p1==NULL || p1->next==NULL || p1->next->next==NULL)
        return false;
    else{
        while(p2->next != NULL){
            p1 = p1->next;
            p2 = p2->next->next;
			if(p1 == p2)
			{
				loop = true;
				break;
			}
        }
    }
    return loop;
}

int main(void)
{
	printf("start...\n");
	int arr[5] = {1, 3, 6, 9, 20};
	int arr2[5] = {4, 8, 10, 12, 30};

	LinkedList L;

#if 0
	L = createCircle(arr);
	joseph(L, 5, 2);
	//printClircleTest(L);
#endif


	//L = createH(arr);
	L = createT(arr);
	print(L);

	LinkedList L2;
	L2 = createT(arr2);
	print(L2);

	L = Merge(L, L2);
	print(L);

#if 0
	InsertionSort(L);
	print(L);



	L = reverse(L);
	print(L);

	L = insert(L, 3, 100);
	print(L);

	L = deldata(L, 1);
	print(L);
#endif


	return 0;
}