数据结构实验之链表四：有序链表的归并

1.知识点：有序链表归并
2.题意：分别输入两个有序的整数序列（分别包含M和N个数据），建立两个有序的单链表，将这两个有序单链表合并成为一个大的有序单链表，并依次输出合并后的单链表数据
3.注意事项：注意若两个链表有一个为空链表的情况、注意合并时一个链表节点已经无节点和一个链表仍含有节点的情况

代码：

#include <stdio.h>
#include <stdlib.h>
struct st
{
    int num;
    struct st *next;
};
struct st * f(struct st *head1, struct st *head2)
{
    struct st *p1, *p2, *tail;
    p1 = head1 -> next;
    p2 = head2 -> next;
    head1 -> next = NULL;
    tail = head1;
    free(head2);/*释放申请的内存*/
    while(p1&&p2)/*两个链表都不为空*/
    {
        if(p1->num < p2->num)
        {
            tail -> next = p1;
            tail = p1;
            p1 = p1 -> next;
            tail -> next = NULL;
        }
        else if(p1->num >= p2->num)
        {
            tail -> next = p2;
            tail = p2;
            p2 = p2 -> next;
            tail -> next = NULL;
        }
    }
    /*判断那一个链表仍含有待插入节点*/
    if(p1)
        tail -> next = p1;
    else
        tail -> next = p2;
    return (head1);
}
int main()
{
    struct st *head1, *head2, *p1, *p2, *tail1, *tail2;
    int M, N, i;
    head1 = (struct st*)malloc(sizeof(struct st));/*动态申请内存*/
    head2 = (struct st*)malloc(sizeof(struct st));/*动态申请内存*/
    p1 = head1 -> next;
    p2 = head2 -> next;
    scanf("%d %d", &M, &N);
    tail1 = head1;
    for(i = 0; i < M; i++)
    {
        p1 = (struct st *)malloc(sizeof(struct st));
        scanf("%d", &p1 -> num);
        /*顺序建立链表*/
        p1 -> next = NULL;
        tail1 -> next = p1;
        tail1 = p1;

    }
    tail2 = head2;
    for(i = 0; i < N; i++)
    {
        p2 = (struct st *)malloc(sizeof(struct st));
        scanf("%d", &p2 -> num);
        /*顺序建立链表*/
        p2 -> next = NULL;
        tail2 -> next = p2;
        tail2 = p2;

    }
    head1 = f(head1, head2);/*链表的归并*/
    p1 = head1 -> next;
    while(p1 != NULL)
    {
        printf("%d%c", p1->num, p1->next == NULL? '\n': ' ');
        p1 = p1->next;
    }
    return 0;
}