单链表相关操作实现

1. 带头结点单链表基本操作

1.1 头文件声明及结构体定义

#include <stdio.h>
#include <stdlib.h>

typedef struct temp
{
	int data;
	struct temp *next;
}Node;

1.2 输入数据创建单链表，遇0结束

Node *creat()
{
	int data;
	Node *head, *p, *q;
	head = (Node *)malloc(sizeof(Node));
	head->next = NULL;

	p = head;
	while (scanf("%d", &data) && data)
	{
		q = (Node *)malloc(sizeof(Node));
		q->data = data;
		q->next = NULL;

		p->next = q;
		p = p->next;
	}
	return head;
}

1.3 单链表测长及打印

int length(Node *head)
{
	int ret = 0;
	Node *p = head->next;
	while (p) 
	{
		p = p->next;
		ret++;
	}
	return ret;
}

void print(Node *head)
{
	Node *p = head->next;
	while (p)
	{
		printf("%d ", p->data);
		p = p->next;
	}
	printf("
");
}

1.4 删除单链表第 i （0 ≤ i ≤ length-1）个结点

int del(Node *head, int num)
{
	int i = -1;
	Node *p, *q;

	p = head;//p->next->next保证第i个结点存在
	while(i<num-1 && p->next && p->next->next)
	{
		p = p->next;
		i++;
	}
	if (i != num-1) return 0;

	q = p->next;
	p->next = q->next;
	free(q);
	return 1;
}

1.5 在单链表第 i （0 ≤ i ≤ length）个结点前插入一个元素

int insert(Node *head, int num, int data)
{
	int i = -1;
	Node *p, *q;

	p = head;
	while(i<num-1 && p->next)
	{
		p = p->next;
		i++;
	}
	if (i != num-1) return 0;

	q = (Node *)malloc(sizeof(Node));
	q->data = data;

	q->next = p->next;
	p->next = q;
	return 1;
}

1.6 单链表的排序（冒泡排序）

void sort(Node *head)
{
	int i, j, n, temp, flag = 1;
	Node *p;

	n = length(head);
	for (i = 1; i < n && flag == 1; i++)
	{
		flag = 0;
		p = head->next;
		for (j = 0; j < n-i; j++)
		{
			if (p->data > p->next->data)
			{
				flag = 1;
				temp = p->data;
				p->data = p->next->data;
				p->next->data = temp;
			}
			p = p->next;
		}
	}
}

1.7 单链表的逆置

void reverse(Node *head)
{
	Node *p, *q, *s;

	if (head->next == NULL) return;
	p = head->next;
	q = p->next;	
	while (q)
	{
		s = q->next;
		q->next = p;
		p = q;
		q = s;
	}

	head->next->next = NULL;//注意链表结尾置空。
	head->next = p;
}

程序验证（未考虑链表的释放）

int main()
{
	Node *head;

	head = creat();
	printf("length of list: %d
", length(head));
	printf("element of list: ");
	print(head);

	del(head, 0);
	printf("after delete the 0th number: ");
	print(head);

	insert(head, 4, 11);
	printf("insert 11 before 4th number: ");
	print(head);

	sort(head);
	printf("element of list after sorted: ");
	print(head);

	reverse(head);
	printf("element of list after reverse: ");
	print(head);

	return 0;
}