完整代码:插入,查找,删除

struct BST {    int val;    BST *lch, *rch;    BST *insert(BST *p, int x) {        if (p == NULL)  {            BST *t = new BST;				//new出来的不是指向NULL的            t->val = x;            t->lch = t->rch = NULL;            return t;        }        if (x <= p->val)    p->lch = insert (p->lch, x);        else    p->rch = insert (p->rch, x);        return p;    }    bool find(BST *p, int x)   {        if (x == p->val)    return true;        else if (p == NULL) return false;        else if (x <= p->val)    {            return find (p->lch, x);        }        else    {            return find (p->rch, x);        }    }    BST *remove(BST *p, int x)  {			//返回被删除后的新结点的地址        if (p == NULL)  return NULL;        else if (x <= p->val)   p->lch = remove (p->lch, x);        else if (x > p->val)    p->rch = remove (p->rch, x);        else if (p->lch == NULL)    {		//如果需要删除的结点没有左儿子,那么把右儿子提上去            BST *t = p->rch;            delete p;            return t;        }        else if (p->lch->rch == NULL)   {	//如果需要删除的结点的左儿子没有右儿子,那么把左儿子提上去            BST *t = p->lch;            t->rch = p->rch;            delete p;            return t;        }        else    {							//以上两种情况不满足,把左儿子子孙中值最大的结点提上去            BST *t = p->lch;            while (t->rch->rch != NULL) t = t->rch;            BST *r = t->rch;            t->rch = r->lch;            r->lch = p->lch;            r->rch = p->rch;            delete p;            return r;        }        return p;    }}bst;