CS50x Problem Set 5 - Inheritance allows inheriting both alleles from one parent

[BallyCode]

My initially incorrect code passed check50 with this:

        // TODO: Randomly assign current person's alleles based on the alleles of their parents
        aperson->alleles[0] = parent0->alleles[rand() % 2];
        aperson->alleles[1] = parent0->alleles[rand() % 2];

inheriting both alleles from parent0.

The second line should have been aperson->alleles[1] = parent1->alleles[rand() % 2];

I discovered the error when I noticed a person with an OO blood type had parents with OO and BB blood types in the printout of the family.

[BallyCode]

I believe this code will correctly check that a person inherits from both parents but it should be carefully double-checked! It includes a few debugging printfs that are commented out.

Unfortunately, due to the random assignment of alleles, it requires multiple runs of inheritance in order to catch errors.

bool check_inheritance(person *p)
// Returns true if all persons are inheriting from both their parents. Returns false if error.
{
    if (p == NULL)
    {
        return true;
    }
    if (p->parents[0] != NULL) // no need to check for parents[1], since a person can't have only one parent
    {
        bool match = (p->alleles[0] == p->parents[0]->alleles[0] || p->alleles[0] == p->parents[0]->alleles[1]) &&
            (p->alleles[1] == p->parents[1]->alleles[0] || p->alleles[1] == p->parents[1]->alleles[1]);
        if (! match)
        {
            // printf("ERROR FOUND in person%p\n", &p);
            return false;
        }
        else
        {
            return true;
        }
    }
    if (check_inheritance(p->parents[0]) == true)
    {
        return check_inheritance(p->parents[1]);
    }
    else
    {
        return false;
    }
}