Chua bai 2-de cuong -tu giao vien- Cac ban xem lai nhe

#include<stdio.h>
#include<conio.h>
#include<string.h>
#include<stdlib.h>

void nhapin(unsigned a[], int *n)
{
int t,i=0;
do
{
printf( "a[%d]= ",i+1);
scanf("%d",&t);
a[i]=t;
*n=i;
i++;
} while (t != 0);
}

void sapxep(unsigned a[], int n)
{
int i, j, tg;
for(i =0; i<n; i++)
for(j =i+1; j<n; j++)
{
if(a[i] < a[j])
{
tg = a[i];
a[i] = a[j];
a[j] = tg;
}
}
for(i =0; i<n; i++)
printf(" %u ", a[i]);
}

long luythuanhiphan(int j, int b)
{
long tam;
int i;
tam=1;
for (i=0;i<j;i++)
tam=tam*b ;
return tam;
}
long luythuacosokhac(int k, int b)
{
long lt=1;
for(int i=0;i<=k;i++)
{
lt=lt*b;
}
return lt;
}

long chuyendoi(char d[],int b)
{
int k,i;
char x[1];
long tp;
k=0; tp=0;
if (b==2)//Neu la so nhi phan
{
for(i=strlen(d);i>=0;i--)
{
if (d[i]=='1')
tp=tp+luythuanhiphan(k,b);
k++;
}
}
else // la co so khac
{
x[0]=d[strlen(d)-1];
tp=tp+atol(x);
int t=strlen(d)-2 ;
for(int i=0;i<=strlen(d)-2;i++)
{
x[0]=d[i];
tp=tp+atol(x)*luythuacosokhac(t,b); //ham atol chuyen xau thanh so
t--;

}
}
return tp ;
}


void main()
{
char d[20];
unsigned a[50];

int b,n, chon=0;
while(chon < 3)
{
clrscr();
printf("\n ************ BAI THI MON EPC ***************\n\n");
printf("********************************************************************");
printf("\n");
printf("* Ngay thang nam sinh: *");
printf("\n");
printf("* Ten sinh vien:*");
printf("\n");
printf("* Ma so sinh vien: *");
printf("\n");
printf("* *");
printf("\n");
printf("* Xin moi ban chon 1 trong 3 lua chon sau: *");
printf("\n");
printf("* 1. Bai tap 2. *");
printf("\n");
printf("* 2. Bai tap 3. *");
printf("\n");
printf("* 3. Thoat chuong trinh. *");
printf("\n");
printf("********************************************************************");

printf("\n\n Ban chon: ");
scanf("%d", &chon);

switch (chon)
{
case 1:

clrscr();
printf("\n Nhap co so dem: ");
scanf("%d", &b);

printf("\n Co so can chuyen: ");
scanf("%s", &d);
if (b==10) //neu la so thap phan thi in ngay
printf("So thap phan la: %s", d);
else
printf("So vua chuyen la:%ld",chuyendoi(d, b));
getch();
break;

case 2:

clrscr();
printf("\n Tong so nguyen duong nhap: ");
nhapin(a,&n );
getch();
printf("\n\n\n Danh sach sau khi sap xep: ");
sapxep(a, n);
getch();
break;
}
}
getch();
}