void RBTreeDelete(RBTree z)
{
	RBTree x,y;
	if(z->left == nil || z->right == nil)
		y = z;
	else 
		y=TreeSuccessor(z);   //y為z的中序後繼

	if(y->left != nil)
		x = y->left;
	else
		x = y->right;

	x->parent = y->parent;
	if(y->parent == nil)
		root = x;
	else
	{
		if(y == y->parent->left)
			y->parent->left  = x;
		else
			y->parent->right = x;
	}
	if(y != z)
		z->key = y->key;
	if(y->color == BLACK)
		RBTreeDeleteFixup(x);
	free(y);    //VC6.0下這句好像有問題，可註釋掉。
}
 

void RBTreeDeleteFixup(RBTree x)
{
	RBTree w;
	while(x != root && x->color == BLACK){
		if(x == x->parent->left){
			w = x->parent->right;
			if(w->color == RED){										//case 1
				w->color = BLACK;
				x->parent->color = RED;
				LeftRotate(x->parent);
				w = x->parent->right;
			}
			if(w->left->color == BLACK && w->right->color == BLACK){       //case 2	
				w->color = RED;
				x = x->parent;
			}
			else{			
				if(w->right->color == BLACK){			       //case 3
					w->left->color = BLACK;
					w->color       = RED;
					RightRotate(w);
					w = x->parent->right;
				}
				w->color = x->parent->color;			       //case 4
				x->parent->color = BLACK;
				w->right->color  = BLACK;
				LeftRotate(x->parent);
				x = root;
			}
		}
		else{
			w = x->parent->left;
			if(w->color == RED){
				w->color = BLACK;
				x->parent->color = RED;
				RightRotate(x->parent);
				w = x->parent->left;
			}
			if(w->left->color == BLACK && w->right->color == BLACK){
				w->color = RED;
				x = x->parent;
			}
			else{ 
				if(w->right->color == BLACK){
					w->left->color = BLACK;
					w->color       = RED;
					LeftRotate(w);
					w = x->parent->left;
				}
				w->color = x->parent->color;
				x->parent->color = BLACK;
				w->left->color   = BLACK;
				RightRotate(x->parent);
				x = root;
			}
		}
	}    //endwhile
	x->color = BLACK;
}