Programs in turboc3: Recursions - factorial,multiplication,power,GCD,Fibonacci,Towers of hanoi

/*Factorial of a number 'n' i.e below 8 using recursion  */

#include<stdio.h>
#include<conio.h>
#include<string.h>
#include<math.h>
int fact(int n);  /* function declaration */
void main()
{
  int n,f;
  clrscr();
  printf(“enter any value:”);
  scanf(“%d”,&n);
  f=fact(n);          /* calling function */
  printf(“\n factorial of %d is %d”,n,f);
  getch();
}

int fact (int n)    /* called function */
{
  int f;
  if(n==1)
  return 1;
  f=n*fact(n-1);
  return (f);
}

Output:

/*Factorial of a number 'n' i.e above 8 using recursion  */

#include<stdio.h>

#include<conio.h>

long factr(int); /* function declaration */

void main()

{

 long fact;

 int n;

 clrscr();

 printf("enter any value:\n");

 scanf("%d",&n);

 fact=factr(n);    /* calling function */

 printf("factorial of %d = %ld",n,fact);

 getch();

 }

 long factr(n)   /* called function */

  {

  long fac;

  if(n==1)

  return 1;

  fac=n*factr(n-1);

  return (fac);

  }

/*Multiplication of two numbers using recursion*/

#include<stdio.h>
#include<conio.h>
#include<string.h>
#include <math.h>
int mult (int,int)    /* function declaration */
void main()
{
  int a,b,c;
  clrscr();
  printf(“enter any two numbers:”);
  scanf(“%d%d”,&a,&b);
  c=mult(a,b);     /* calling function */
  printf(“multiplication of %d and %d is %d”,a,b,c);
  getch();
}

int mult (int a,int b)    /* called function */
{
   if(b==1)
   return a;
   c=b+mult(a,b-1);
   return (c);
}

Output: 

/*Power of two numbers using recursion*/

#include<stdio.h>
#include<conio.h>
#include<string.h>
#include<math.h>
int a,b,c;
int pow(int,int);
void main()
{
  int c;
clrscr();
printf(“enter any two numbers:”);
scanf(“%d%d,&a,&b);
c=pow(a,b);
printf(“\n power of %d and %d is %d”,a,b,c);
getch();
}

int pow (int a,int b)
{
   int c;
   if(b==0)
   return 1;
   c=a*pow(a,b-1);
   return (c);
}

Output:

/*GCD of two numbers using recursion*/

#include<stdio.h>

#include<conio.h>

int gcd(int,int); /* function declaration */

void main()

{

 int a,b,c;

 clrscr();

 printf("\n enter any two values:\n");

 scanf("%d%d",&a,&b);

 c=gcd(a,b);   /* calling function */

 printf("GCD of %d and %d = %d",a,b,c);

 getch();

}

 int gcd(int m,int n)    /* called function  */

 { int x;

  if(n==0)

  return m;

  if(n>m)

   return (gcd(n,m));

  else

   x=m%n;

  return(gcd(n,x));

 }

Output:

/* Fabinacci series using recursion*/

#include<stdio.h>

#include<conio.h>

int n,fib;   /* global variable */

int fibon(int); /* function declaration */

void main()

{

 int i;

 clrscr();

 printf("enter any value:\n");

 scanf("%d",&n);

 printf("\n Fabinacci series of %d: \n",n);

 for(i=0;i<n;i++)

 {

 fib=fibon(i);     /* calling function */

 printf("%d\t",fib);

 }

 getch();

}

 int fibon(n)  /* called function */

 {

  int a,b;

  if(n<=1)

  return n;

  a=fibon(n-1);

  b=fibon(n-2);

  return (a+b);

 }

Output:

/* Towers of Hanoi using recursion */

#include<stdio.h>

#include<conio.h>

void hanoi(int,char,char,char); /* function declaration */

void main()

{

 int n;

 clrscr();

 printf("\n Enter no. of disks to be moved:\n");

 scanf("%d",&n);

 hanoi(n,'X','Z','Y');

 getch();

}

 void hanoi(int n,char initial,char final,char temp)

 {

  if(n==1)

  {

  printf("move disk 1 from needle  %c to %c\n",initial,final);

  return;

  }

 hanoi(n-1,initial,temp,final);

 printf("move disk %d from needle  %c to %c\n",n,initial,final);

 hanoi(n-1,temp,final,initial);

 }

output: