C語言-創建鏈表及排序

#include <stdio.h>
#define NEWNODE (Node *)malloc(sizeof(Node)) 

typedef struct mynode{
    int num;
    struct mynode *next;
}Node;

Node* creat(){
    Node *head=NULL,*p,*q;
    //head:表頭，q:表尾 
    q=p=NEWNODE;
    scanf("%d",&p->num);
    p->next=NULL;
    while(p->num>0){
        if(head==NULL){
            head=q=p;
        }else{
            q->next=p;
            q=p;
        }
        p=NEWNODE;
        scanf("%d",&p->num);
        p->next=NULL;
    }
    return head;
}

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

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

//選擇排序-交換結點 
Node *select_sort(Node *head){
    Node *begin=NULL,*end=NULL;    //有序鏈表的首尾結點指針
    Node *p;
    Node *min,*premin;    //最小結點及其前一個結點
    if(!head)return NULL;
    while(head){
        //循環找出無序鏈表中的最小結點min及其前一個結點premin
        p=head;
        min=p;
        while(p->next){
            if(min->num>p->next->num){
                premin=p;
                min=p->next;
            }
            p=p->next;
        }
        //1. 將min接入有序鏈表 
        //如果有序鏈表為NULL 
        if(begin==NULL){
            begin=end=min;
        }else{
            end->next=min;
            end=min;
        }
        //2. 在無序鏈表中刪除結點min
        if(min==head){
            head=min->next;
        }else{
            premin->next=min->next;
        }         
    }
    end->next=NULL;
    return begin;    
}

//冒泡排序-交換值 
void pubble_sort(Node *head)
{
    Node *end;
    int t;
    Node *p,*pre;
    p=head;
    //end~NULL為有序部分，將end置為尾結點 
    while(p->next)p=p->next;
    end=p;
    //每輪冒泡end左移一個結點，一直到head與end重合 
    while(head!=end){
        p=head;
        while(p!=end){
            if(p->num>p->next->num){
                t=p->num;
                p->num=p->next->num;
                p->next->num=t;
            }
            pre=p;
            p=p->next;
        }
        end=pre;
    }
}



int main()
{
    Node *head;
    head=creat();
    
    pubble_sort(head);
    
    print(head);
    
    return 0;
}