链式存顺序找

#include "stdio.h"
typedef char keytype ;
typedef struct rectype
{
    keytype key;
    struct rectype *next;
}*RT,rec;
RT build()
{
    char ch;
    RT head=(RT)malloc(sizeof(rec));
    RT r,s;
    r=head;
    ch=getchar();
    while(ch!='\n')
    {
        s=(RT)malloc(sizeof(rec));
        s->key=ch;
        r->next=s;
        r=s;
        ch=getchar();
    }
    return head;
}
RT seqsearch(RT head,keytype k)
{
    RT p;
    p=head;
    while((p!=NULL)&&(p->key!=k))
    {