CODEWITHSUNDEEP
javarecursionfactorial
user1730357
user1730357

Reputation: 355

How do I print factorials without using a loop?

I made a recursive method to calculate factorials, but in the main method I have used a for loop to calculate the list of factorials. Is there a way to calculate a list of factorials without using a loop in the main method?

Code:

public class FactInt {
    public static void main(String[] args) {
        for (int n = 1; n < 11; n++)
            System.out.println(factorial(n));
    }
    //Calculates the factorial of integer n
    public static int factorial(int n) {
        if (n == 0)
            return 1;
        else 
            return n*factorial(n-1);
    }
}

Upvotes: 0

Views: 17179

Answers (5)

Paolo
Paolo

Reputation: 1691

Use recursion again like this!

public class FactInt {
    public static void main(String[] args) {

        factorialList(1, 10);
    }
    //Calculates the factorial of integer n
    public static int factorial(int n) {
        if (n == 0)
            return 1;
        else 
            return n*factorial(n-1);
    }

    public static void factorialList(int min, int max) {
        if (min != max)
            factorialList(min, max-1);
        System.out.println(factorial(max));
    }
}

Upvotes: 0

vallentin
vallentin

Reputation: 26157

Actually I would want to say you can't or more like well why would you, but well if you really want to, you could do it like this.

public class FactInt {
    public static void main(String[] args) {
        factorial(10);
    }
    //Calculates the factorial of integer n
    public static int factorial(int n) {
        final int calc;

        if (n == 0) { calc = 1; }
        else { calc = n * factorial(n - 1); }

        System.out.println(calc);

        return calc;
    }
}

Upvotes: 0

Shamse Alam
Shamse Alam

Reputation: 1315

Create a method say getFactorial(int num) as follows. Move your for loop inside that method and call that method from main.

 public static void main(String[] args) {
    int num = 11;
   getFactorial(num);
}

public static void getFactorial(int num){
    for (int n = 1; n < num; n++)
        System.out.println(factorial(n));
}
//Calculates the factorial of integer n
public static int factorial(int n) {
    if (n == 0)
        return 1;
    else 
        return n*factorial(n-1);
}

Upvotes: 0

rgettman
rgettman

Reputation: 178263

I don't know why you don't want to use a loop, but here's a couple ideas:

Unroll the loop yourself.

System.out.println(factorial(1));
System.out.println(factorial(2));
// ...
System.out.println(factorial(11));

Make another recursive method and call it from main.

public static void factorials(int n)
{
    if (n >= 11) return;
    System.out.println(factorial(n));
    factorials(n + 1);
}

Upvotes: 0

Tim S.
Tim S.

Reputation: 56536

It depends on exactly what you mean by "calculate a list", but this prints the same thing:

public static void main(String[] args) {
    factorial(10);
}
//Calculates the factorial of integer n
public static int factorial(int n) {
    if (n == 0)
        return 1;
    else {
        int newVal = n*factorial(n-1);
        System.out.println(newVal);
        return newVal;
    }
}

Upvotes: 8

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