Red black tree deletion problem

[renz15]

Hello, I am making a code for a red black tree. The insert is working but there's a problem in my code when it comes to deleting the node. These are the cases that work:

• Red Leaf
• The node to be deleted only has one child

The other cases don't work.

Here's my code:

bool isRed(node *y)
{
    return (y!=NIL && y->color!='B');
}

bool isNull(node *x)
{
    return (x==NULL || x==NIL);
}

node* TreeSuccessor(node *z)
{
    if(z->rightchild!=NIL)
    {
        z=z->rightchild;
        while(z->leftchild!=NIL)
            z=z->leftchild;
        return z;
    }

    node *y=z->parent;
    while(y!=NIL && z==y->rightchild)
    {
        z=y;
        y=y->parent;
    }
    return y;
}

int LeftRotate(node* z)
{
    node *y;
    y=z->rightchild;
    z->rightchild=y->leftchild;
    if (!isNull(y->leftchild))
        y->leftchild->parent=z;

    y->parent=z->parent;
    if(isNull(z->parent))
        root=y;
    else if(z==z->parent->leftchild)
        z->parent->leftchild=y;
    else
        z->parent->rightchild=y;

    y->leftchild=z;
    z->parent=y;
    return 0;
}

int RightRotate (node *z)
{
    node *y;
    y=z->leftchild;
    z->leftchild=y->rightchild;

    if(!isNull(y->rightchild))
        y->rightchild->parent=z;

    y->parent=z->parent;

    if(isNull(z->parent))
        root=y;
    else if(z==z->parent->rightchild)
        z->parent->rightchild=y;
    else
        z->parent->leftchild=y;

    y->rightchild=z;
    z->parent=y;
    return 0;
}


int DeleteFix(node *z)
{

    node *y;

    while(z!=root && z->color == 'B')
    {
        if(z==z->parent->leftchild)
        {

            y=z->parent->rightchild;
            if(isRed(y))
            {
                y->color='B';
                z->parent->color='R';
                LeftRotate(z->parent);
                y=z->parent->rightchild;
            }

            if(y->leftchild->color == 'B' && y->rightchild->color == 'B')
            {

                y->color='R';
                z=z->parent;

            }
            else if(y->rightchild->color == 'B')
            {
                y->leftchild->color='B';
                y->color='R';
                RightRotate(y);
                y=z->parent->rightchild;

            }
            y->color=z->parent->color;
            z->parent->color='B';
            y->rightchild->color='B';
            LeftRotate(z->parent);
            z=root;
        }
        else
        {
            y=z->parent->leftchild;
            if(isRed(y))
            {
                y->color='B';
                z->parent->color='R';
                RightRotate(z->parent);
                y=z->parent->leftchild;
            }
            else if(y->leftchild->color == 'B')
                {
                    y->rightchild->color='B';
                    y->color='R';
                    LeftRotate(y);
                    y=z->parent->leftchild;
                }
            }
             y->color=z->parent->color;
             z->parent->color='B';
             y->leftchild->color='B';
             RightRotate(z->parent);
             z=root;

    }
    z->color='B';
    y = NULL;
    cout << root->number;
    return 0;
}

int DeleteNode()
{
    cout << "\t\t========================================\n";
    cout << "\t\t      R E D  B L A C K  T R E E S\n";
    cout << "\t\t========================================\n";
    cout << "\t\t\t\tD E L E T E\n";
    cout << "\t\t----------------------------------------\n";
    int number;
    cout << "Please enter the number to be deleted: ";
    cin >> number;
    node *z;
    for(z=root;z!=NIL;)
    {
        if(number < z->number)
            z=z->leftchild;
        else if(number > z->number)
            z=z->rightchild;
        else if(number==z->number)
            break;
        else if (z==NIL)
        {
            cout << "No such number exists.";
            return 0;
        }
        else
            return 0;
    }
    node *x;
    node *y;
    if (z->leftchild==NIL || z->rightchild==NIL)
        y=z;
    else
        y=TreeSuccessor(z);
    if(y->leftchild!=NIL)
        x = y->leftchild;
    else
        x=y->rightchild;

    x->parent=y->parent;

    if(y->parent==NIL)
        root=x;
    else if(y==y->parent->leftchild)
            y->parent->leftchild=x;
    else
        y->parent->rightchild=x;
    if(y!=z)
        z->number=y->number;
    if(y->color=='B')
    {
            DeleteFix(x);
    }

    return 0;
}