Saturday 2 March 2013

Recursion in java


A recursive method is a method that calls itself either directly or indirectly through another method.  A method call itself is termed as Recursion.
Example:         fact(n) = 1                   ; if n=0
                                       n*fact(n-1)   ; n ³ 1

// Write a program to print the factorial of a given number using recursion

class a
{
            double fact(double x)
            {
            if(x==0)
            return 1;
            else
            return x*fact(x-1);
            }
}
class recur
{
            public static void main(String[] args)
            {
            a obj=new a();
            int p=Integer.parseInt(args[0]);
            double t=obj.fact(p);
            System.out.println("facatorial="+t);
            }
}          

// Write a program to print the first n Fibonacci sequence numbers using recursion
(Lab Program: 2)

class a
{
            int f(int x)
            {
            if(x==0||x==1)
            return x;
            else
            return (f(x-1)+f(x-2));
            }
}
class fibo
{
            public static void main(String[] args)
            {
            a obj=new a();
            int p=Integer.parseInt(args[0]);
            for(int i=1;i<=p;i++)
            {
            int t=obj.f(i);
            System.out.println("    "+t);
            }
            }
}

// Write a program to print the sum of ‘n’ numbers using the recursive formula
            sum (n) = 0                              ; if n = 0
                            n + sum(n-1)            ; if n ³ 1

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