C Program for Binary Search and Towers of Hanoi using Recursion

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main()
{
int n,a[50],key,opn,i,pos;
do
{
clrscr();
printf(" \n\n Press 1 -> Binary Search , 2-> Towers of Hanoi 3-> Quit\n");
scanf("%d",&opn);
switch(opn)
{
case 1: printf(" How Many Elements?");
scanf("%d",&n);
printf(" Read all the elements is ASC order \n");
for(i=1;i<=n;i++)
scanf("%d",&a[i]);
printf(" Read the Key Element\n");
scanf("%d",&key);
pos=BS(a,key,1,n);
if(pos)	 printf(" Success: %d found at %d \n", key,pos);
else	 printf(" Falure: %d Not found in the list ! \n",key);
break;
case 2: printf("\n\n How Many Disks ?");
scanf("%d", &n);
printf("\n\n Result of Towers of Hanoi for %d Disks \n",n);
tower(n,'A','B','C');
printf("\n\n Note: A-> Source, B-> Intermediate, C-> Destination\n");
break;
case 3: printf(" Terminating \n"); break;
default: printf(" Invalid Option !! Try Again !! \n");
}
printf(" Press a Key. . . ");  getch();
}while(opn != 3);
}
int BS(int a[], int key,int low,int high)
{
int mid;
if(low > high) return 0; /* failure */
else
{
mid=(low+high)/2;
if(a[mid]== key) return mid; /* Success */
if(key < a[mid]) return(BS(a,key,low,mid-1));
return(BS(a,key,mid+1,high));
}
}
tower(int n, char src, char intr, char dst)
{
if(n > 0)
{
tower(n-1,src,dst,intr);
printf("Move disk %d from %c to %c \n", n,src,dst);
tower(n-1,intr,src,dst);
}
}

main() { int n,a[50],key,opn,i,pos; do { clrscr(); printf(" \n\n Press 1 -> Binary Search , 2-> Towers of Hanoi 3-> Quit\n"); scanf("%d",&opn); switch(opn) { case 1: printf(" How Many Elements?"); scanf("%d",&n); printf(" Read all the elements is ASC order \n"); for(i=1;i<=n;i++) scanf("%d",&a[i]); printf(" Read the Key Element\n"); scanf("%d",&key); pos=BS(a,key,1,n); if(pos) printf(" Success: %d found at %d \n", key,pos); else printf(" Falure: %d Not found in the list ! \n",key); break; case 2: printf("\n\n How Many Disks ?"); scanf("%d", &n); printf("\n\n Result of Towers of Hanoi for %d Disks \n",n); tower(n,'A','B','C'); printf("\n\n Note: A-> Source, B-> Intermediate, C-> Destination\n"); break; case 3: printf(" Terminating \n"); break; default: printf(" Invalid Option !! Try Again !! \n"); } printf(" Press a Key. . . "); getch(); }while(opn != 3); } int BS(int a[], int key,int low,int high) { int mid; if(low > high) return 0; /* failure */ else { mid=(low+high)/2; if(a[mid]== key) return mid; /* Success */ if(key < a[mid]) return(BS(a,key,low,mid-1)); return(BS(a,key,mid+1,high)); } } tower(int n, char src, char intr, char dst) { if(n > 0) { tower(n-1,src,dst,intr); printf("Move disk %d from %c to %c \n", n,src,dst); tower(n-1,intr,src,dst); } }