C实现单链表直接选择排序

/****************************单链表直接选择排序*******************************/#include<stdio.h>#include<stdlib.h>struct node{    int num;    struct node *next;};struct node *head=NULL;cre_list() //初始化结点{    head = (struct node *)malloc(sizeof(struct node));head->num=0;    head->next = NULL;}add_node(int num) //插入结点{    struct node *ptr = (struct node *)malloc(sizeof(struct node));    ptr->num = num;ptr->next = head->next;    head->next=ptr;}display_node() //遍历链表{    struct node *p = head->next;    do    {        printf("%d\t",p->num);        p = p->next;    }while(p != NULL);    printf("\n");}select_insert(){    int min=0;int tmp=0;    struct node *p,*q,*M;p=q=M=head;while(p->next!=NULL){    M=q=p->next;min=q->num;while(q!=NULL){    if(q->num < min)    {        M=q;min=q->num;    }q=q->next;}if(p->next!=M){    tmp=p->next->num;p->next->num=M->num;M->num=tmp;}p=p->next;}}int main(){    int i;    int a[10]={23,41,77,12,98,25,6,97,55,38};    cre_list();    for(i=0;i<10;i++)    {        add_node(a[i]);    }    display_node();select_insert();    display_node();    return 0;}