Question

How can I get this recursive method to return 1 on calling 0! without testing for a base case, that is without doing an if-else for 0 and 1.

public static long f( number ){
        if ( number <= 1 ){ // test for base case
                return 1; // base cases: 0! = 1 and 1! = 1
            } 
        else{ return number * f( number - 1 ); }
   }

I don’t want to check for base cases. Is this possible?

Answer 1

Using an if-else or ? : is the best solution. I.e. anything els eis likely to be worse.

public static long f(int n){
  try {
    return 0 / n + n * f(n-1);
  } catch(ArithmeticException ae) {
    return 1;
  }
}