What does the output statement in main() print out? What is wrong with the implementation of factorial() in this class?

Question

```
public class BadFactorial {
private int n;
public static long factorial () {
if ( n == 1 ) // base case; recursion ends
return 1; // return a result
else {
// recursive case: update input size to
// get closer to base case and iterate again
n = n – 1;
return n * factorial();
}
}

public static main() {
n = 4;
System.out.println("factorial 4 is " + factorial() );
}
}

```

Answer 1

It will print out: “factorial 4 is 6” instead of the actual factorial of 4, which is 24. This is because n is decremented before it is multiplied with the recursive call. The method factorial() will basically be returning the result of this expression: 3 * 2 * 1 * 1.

Commenting out the line n = n – 1; and changing the line that follows it to
return n-- * factorial(); solves the problem.