//PROGRAM USING RECURSSIVE FUNCTION

#include<stdio.h>

int fact(int x)
{
if(x<=1)
return 1;
else return(x*fact(x-1));
}
int fibo(int x)
{
if(x<=1)
return 1;
else
return(fibo(x-1)+fibo(x-2));
}
void main()
{
int x,i,n,r,s,ans,ch;
char cha;
clrscr();
do
{
clrscr();
printf("1:Fibonancci\n2:Factorial\n3:Binomial Coiefficent\n");
printf("Enter your choice");
scanf("%d",&ch);

switch(ch)
	 {
	 case 1:
		 printf("enter the no of terms");
		 scanf("%d",&x);
		 printf("fibonancci series\n");
		 printf("0");
		 for(i=0;i<(x-1);i++)
			 {
			 ans=fibo(i);
			 printf("%2d",ans);
			 }
		 break;

	 case 2:
		 printf("enter no whose factorial is to be calculated");
		 scanf("%d",&x);
		 ans=fact(x);
		 printf("factorial value=%d",ans);
		 break;
	 case 3:
		 printf("enter the values of n and r :");
		 scanf("%d%d",&n,&r);
		 if(n<r)
			printf("n should be greater trhan or equal to r");
		 else
			{
			s=fact(n)/(fact(r)*fact(n-r));
			printf("the answer is %d",s);
			}
		 break;
	 }

printf("\nDo you want to continue or not y/n\n");
fflush(stdin);

scanf("%c",&cha);
}
while(cha=='y');
getch();
}
/*SAMPLE OUTPUT

1:Fibonacci
2:Factorial
3:Binomial coeifficent
enter your choice1
enter the no of terms5
fibonacci series
0 1 1 2 3
do you want to continue or not
y/n
y
________________________________________

1:Fibonacci
2:Factorial
3:Binomial coeifficent
enter your choice2
enter the no whose factorial is to be calculated
factorial value=120
Do you want to continue or not y/n
y
_______________________________________

1:Fibonancci
2:Factorial
3:Binomial Coiefficent
Enter your choice3
enter the values of n and r :4 2
the answer is 6
Do you want to continue or not y/n
n
_______________________________________
*/