ThemBotPhanTu_dsLR_FamiHug

#include<stdio.h>
#include<stdlib.h>
//By FamiHug
typedef struct dslkk{
    int info;
    struct dslkk *rptr;
    struct dslkk *lptr;
} dslr;

dslr *r,*t,*l,*n,*p,*f,*m;
void insert_after(dslr*,int);
void delete(dslr*);
int k,i,temp;

int main()
{
    r=NULL;
    l=NULL;
    m=NULL;
    n=NULL;
    t=NULL;


    printf("CHUONG TRINH BO SUNG 1 PHAN TU VAO SAU PHAN TU TRO BOI M\n");
    printf("________________VA XOA PHAN TU TRO BOI M________________\n");
    printf("Nhap so phan tu cua danh sach: ");
    scanf("%d",&k);

    if(k>=0)
    {
    int i;

    for(i=1;i<=k;i++)
    {
        p=(dslr *)malloc(sizeof(dslr)); //con tro luon tro den ben phai cua ds

        if(t==NULL)
        {
            p->lptr=NULL;
            t=p;
        }
        else
        {
            p->lptr=t;
            t=p;
        }
    }

    r=p;//r tro den phan tu cuoi cung cua ds

    for(i=1;i<=k;i++)
    {
        if(n==NULL)
        {
            p->rptr=NULL;
            n=p;
        }
        else
        {
            p->rptr=n;
            n=p;
        }
        if(i<k)
        p=p->lptr;
    }
    l=p;//l tro den ptu dau tien cua ds


    //

    //Nhap noi dung cho cac phan tu
    p=l;
    for(i=1;i<=k;i++)
    {
        printf("Phan tu thu %d: ",i);
        scanf("%d",&p->info);
        p=p->rptr;}
//in danh sach vua nhap
    printf("Danh sach vua nhap la: ");
    p=l;
    while(p!=NULL)
    {
        printf("%3d",p->info);
        p=p->rptr;
    }
//Them lan 1
    m=l;
    if(k>0)
    {
    printf("\nM dang tro den phan tu dau tien, thuc hien them phan tu vao sau M.\n");
}
    else
    printf("Danh sach dang rong. Them phan tu vao.\n");
    printf("Noi dung phan tu la: ");
    scanf("%d",&temp);
    insert_after(m,temp);

    p=l;
    printf("Danh sach sau khi them la: ");
    while(p!=NULL)
    {
        printf("%3d",p->info);
        p=p->rptr;
    }
    //Xoa
    printf("\nXOA PHAN TU TRO BOI M\n");
    delete(m);
    printf("Danh sach sau khi xoa la: ");
    p=l;
    while(p!=NULL)
    {
        printf("%3d",p->info);
        p=p->rptr;
    }


}   else
    printf("So nhap vao khong hop le. Chuong trinh ket thuc");
    return 1;
}


/*Cac Chuong trinh con*/
void insert_after(dslr* m,int x)
{
    dslr* f;
        if((r==NULL)&&(l==NULL))
    {
        m=(dslr *)malloc(sizeof(dslr));
        m->info=x;
        m->lptr=NULL;
        m->rptr=NULL;
        l=r=m;
    }
    else if(l==r)
        {
            f=(dslr *)malloc(sizeof(dslr));
            f->info=x;

            f->lptr=m;
            m->rptr=f;
            f->rptr=NULL;
            r=f;

         }
         else
         {
            f=(dslr *)malloc(sizeof(dslr));
            f->info=x;

            m->rptr->lptr=f;
            f->rptr=m->rptr;
            m->rptr=f;
            f->lptr=m;
        }
}



void delete(dslr *m)
{

    if (l==NULL)
    printf("Danh sach khong co phan tu nao");
    else
        if(l==r)
        {
            r=NULL;
            l=NULL;
            free(m);
        }
            else
                if(l==m)
                {
                    m->rptr->lptr=l;
                    l=m->rptr;
                    free(m);
                }
                else
                    if(r==m)
                    {
                        m->lptr->rptr=r;
                        r=m->lptr;
                        free(m);
                    }
                    else//ko dau ko cuoi
                    {
                        m->lptr->rptr=m->rptr;
                        m->rptr->lptr=m->lptr;
                        free(m);
                    }
                }