大链表数据的排序

typedef struct _node_t{ int a; struct _node_t* next;}node_t;node_t* Mergesort(node_t* L,int count) //链表头及要链表元数个数{if(count==1) return L;int count1=count/2;int count2=count-count1;node_t* p=L;int i;for(i=0;i<count1;i++) p=p->next;node_t* h1=Mergesort(L,count1);node_t* h2=Mergesort(p,count2);int t1=0,t2=0;node_t *head=NULL,*cur;while(t1<count1||t2<count2) {if(t1<count1&&t2<count2) {if(h1->a < h2->a) p=h1,h1=h1->next,t1++;else p=h2,h2=h2->next,t2++;}else if(t1<count1) p=h1,h1=h1->next,t1++;else p=h2,h2=h2->next,t2++;if(head==NULL) head=cur=p;else {cur->next=p;cur=p;}}return head;}void sort(node_t* &a){int count=0;node_t* p=a;while(a) {count++;a=a->next;}a=Mergesort(p,count);p=a;int i;for(i=0;i<count-1;i++) p=p->next;p->next=NULL;}void input(node_t* &a){a=NULL;int n;node_t* p;while(true) {scanf("%d",&n);node_t* s= new node_t;s->a=n;if(a==NULL) a=p=s;else p->next=s;p=s;p->next=NULL;if (n==0){break;}}}void output(node_t* a){while(a) {printf("%d ",a->a);a=a->next;}printf("//n");}int main(){node_t* a;//freopen("test.in","r",stdin);input(a);//屏幕输入时输一串数字，然后按enter再按ctrl+z结束sort(a);output(a);return 0;}