• Write a function that returns the value of the father of a given element in a binary tree of integers without repetition.
  • Write a function that returns an array containing the values of all ancestors of a given element in a binary tree of integers without repetition ordered from the nearest to the farthest.
    Example: the sorted ancestors of 3 in the following tree are: 2, 5, 10.
  • Write a function that returns the value of the nearest common ancestor of two given elements in a binary tree of integers without repetition.
    Example: the nearest common ancestor of 3 and 9 is 5.
Difficulty level
This exercise is mostly suitable for students 
int father(Btree A, element e, element *p)
{
    if (A==NULL || (A->left==NULL && A->right == NULL)) return 0;
    if (A->left &&  A->left->data==e || A->right && A->right->data == e)
    {
        *p = A->data;
        return 1;
    }
    if(father(A->left,e,p)) return 1;
    return father(A->right,e,p);
}


void ancestors(Btree A, element e, element tab[],int *N)
{
    element p;
    *N=0;
    while(father(A,e,&p))
    {
        tab[*N] = p;
        e = p;
        (*N)++;
    }
}


int nearest_common_ancestor(Btree A, element e1, element e2, element *anc)
{
    element tab1[100],tab2[100];
    int N1,N2,i1,i2;
    ancestors(A,e1,tab1,&N1);
    ancestors(A,e2,tab2,&N2);
    for (i1=0 ; i1<N1 ; i1++)
        for (i2=0; i2<N2; i2++)
            if (tab1[i1] == tab2[i2])
            {
                *anc = tab1[i1];
                return 1;
            }
    return 0;
}
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