Data Structures and Algorithms - Old Questions

6. What is recursion? Write a recursive program to find factorial of a number.

Recursion is a process by which a function calls itself repeatedly, until some specified condition has been satisfied. The process is used for repetitive computations in which each action is stated in terms of a previous result.

In order to solve a problem recursively, two conditions must be satisfied. First, the problem must be written in a recursive form, and second, the problem statement must include a stopping condition.

Recursive program to find factorial of a number:

#include<stdio.h>

#include<conio.h> 

void main( )

{

clrscr( );

 int factorial(int);

 int n,f;

 printf("Enter the number: ");

 scanf("%d",&n);

 f=factorial(n);

 printf("Factorial of the %d number is %d",n,f);

 getch();

}

int factorial(int n)

{

  int f;

  if(n==1)

     return 1;

  else

     f=n*factorial(n-1);

     return f;

}