单链表

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

typedef struct student {
    int data;
    struct student *next;
}node;

node *create()
{
    node *head, *p, *s;
    int x, cycle = 1;
    head = (node *)malloc(sizeof(node));
    p = head;

    while (cycle)
    {
        printf("\nplease input the data: ");
        scanf("%d", &x);

        if (x != 0)
        {
            s = (node *)malloc(sizeof(node));
            s->data = x;
            p->next = s;
            p = s;
        }
        else
        {
            cycle = 0;
        }
    }

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

int length(node *head)
{
    int n = 0;
    node *p;
    p = head;

    while (p != NULL)
    {
        p = p->next;
        n++;
    }
    return n;
}

void print(node *head)
{
    node *p;
    int n;

    n = length(head);
    p = head;

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

    printf("\n");
}

node *del(node *head, int value)
{
    node *p1, *p2;

    p1 = head;

    while ((value != p1->data) && (p1->next != NULL))
    {
        p2 = p1;
        p1 = p1->next;
    }

    if (value == p1->data)
    {
        if (p1 == head)
        {
            head = p1->next;
            free(p1);
        }
        else
        {
            p2->next = p1->next;
            free(p1);
        }
    }
    else
    {
        printf("\n%d could not been found\n", value);
    }
    return head;
}

node *insert(node *head, int value)
{
    node *p0, *p1, *p2;

    p1 = head;
    p0 = (node *)malloc(sizeof(node));
    p0->data = value;

    while ((p0->data > p1->data)&&(p1->next != NULL))
    {
        p2 = p1;
        p1 = p1->next;
    }

    if (p0->data <= p1->data)
    {
        if (p1 == head)
        {
            head = p0;
            p0->next = p1;
        }
        else
        {
            p0->next = p1;
            p2->next = p0;
        }
    }
    else
    {
        p1->next = p0;
        p0->next = NULL;
    }

    return head;
}

node *reverse(node *head)
{
    node *p, *q, *s;

    p = head;
    q = p->next;
    s = q->next;
    p->next = NULL;

    while (s->next)
    {
        q->next = p;
        p = q;
        q = s;
        s = s->next;
    }

    q->next = p;
    s->next = q;
    head = s;

    return head;
}

node *merge(node *head1, node *head2)
{
    if (head1 == NULL)
    {
        return head2;
    }
    if (head2 == NULL)
    {
        return head1;
    }

    node *head, *p1, *p2;

    if (head1->data < head2->data)
    {
        head = head1;
        p1 = head1->next;
        p2 = head2;
    }
    else
    {
        head = head2;
        p2 = head2->next;
        p1 = head1;
    }

    node *pcurrent = head;
    while (p1 != NULL && p2 != NULL)
    {
        if (p1->data < p2->data)
        {
            pcurrent->next = p1;
            pcurrent = p1;
            p1 = p1->next;
        }
        else
        {
            pcurrent->next = p2;
            pcurrent = p2;
            p2 = p2->next;
        }
    }

    if (p1 != NULL)
        pcurrent->next = p1;
    if (p2 != NULL)
        pcurrent->next = p2;
    return head;
}

int main()
{
    node *head1, *head2;

    head1 = create();
    head2 = create();
    print(head1);
    print(head2);

    head1 = merge(head1, head2);
    print(head1);
    return 0;
}