Checking if a number is Humble

static boolean isPrime(int n)
    {
        if(n<=1) return false;
        if(n==2) return true;
        if(n%2==0) return false;
        int m = (int)Math.round(Math.sqrt(n));

        for(int i=3; i <= m; i+=2)
            if(n%i==0)
                return false;
        return true;
    }

    static boolean isHumble(int n)
    {   
        for(int i = 2; i <= n; i++)
        {
            if (isPrime(i) && isFactor(n, i))
            {
                System.out.println(i);
                //if(isPresent(i))
                //  return false;
                //else return true;
                return true;开发者_运维百科

            }
        }
        return false;
    }

    static boolean isFactor(int val1, int val2)
    {
        return val1%val2==0;
    }

    static boolean isPresent(int n){
        for(int val : prime_factors)
            if(n==val)
                return true;
        return false;
    }

// prime_factors {2,3,5,7}

I am implementing an isHumble function, but for some reason something seems to be off. Can anyone help me out please?

Edit

Add 1 to your list of prime numbers, and try the following:

boolean isHumble(int n)
{
    if (isFactor(n)) return true;
    for(int i=2;i<=n/2;i++)
    {
        while(n%i == 0)
            if (isFactor(i))
                n /= i;
            else
                return false;
    }
    return isFactor(n);
}

So that those factors are removed from the number and not found later.

Edit 2

A simpler solution would be:

boolean isHumble(int n)
{
    for (int val : prime_factors)
        while (n % val == 0) n /= val;
    return (n == 1);
}

As it's written your isHumble method will return false for every number because of the way your isFactor method is written...

A humble number is one whose only prime factors are 2,3,5,7. That means, if you take all the "prime numbers" from 0 to n/2, only 2,3,5,7 should divide them. Instead you are taking all the numbers from 0 to n/2 and checking whether they are factors.

Hence in your case when i=9, the statement if(n%i == 0) returns to true and hence return false is getting executed.

Run your outer loop on i for only prime numbers instead of all the numbers from 0 to n/2 and you should be fine.

Your isFactor method could be easier be written as

boolean isFactor(int n){
    return prime_factors.contains(n);
}