struct node
{
    int val;
    pnode lchild;
    pnode rchild;
};

pnode BT = NULL;

//遞歸方法插入節(jié)點(diǎn)
pnode insert(pnode root, int x)
{
    pnode p = (pnode)malloc(LEN);
    p->val = x;
    p->lchild = NULL;
    p->rchild = NULL;
    if(root == NULL){
        root = p;   
    }   
    else if(x < root->val){
        root->lchild = insert(root->lchild, x);   
    }
    else{
        root->rchild = insert(root->rchild, x);   
    }
    return root;
}

//非遞歸方法插入節(jié)點(diǎn)
void insert_BST(pnode q, int x)
{
    pnode p = (pnode)malloc(LEN);
    p->val = x;
    p->lchild = NULL;
    p->rchild = NULL;
    if(q == NULL){
        BT = p;
        return ;   
    }       
    while(q->lchild != p && q->rchild != p){
        if(x < q->val){
            if(q->lchild){
                q = q->lchild;   
            }   
            else{
                q->lchild = p;
            }       
        }   
        else{
            if(q->rchild){
                q = q->rchild;   
            }   
            else{
                q->rchild = p;   
            }
        }
    }
    return;
}

pnode search_BST(pnode p, int x)
{
    bool solve = false;
    while(p && !solve){
        if(x == p->val){
            solve = true;   
        }   
        else if(x < p->val){
            p = p->lchild;   
        }
        else{
            p = p->rchild;   
        }
    }
    if(p == NULL){
        cout << "沒有找到" << x << endl;   
    }
    return p;
}

bool delete_BST(pnode p, int x) //返回一個(gè)標(biāo)志，表示是否找到被刪元素
{
    bool find = false;
    pnode q;
    p = BT;
    while(p && !find){  //尋找被刪元素
        if(x == p->val){  //找到被刪元素
            find = true;   
        }   
        else if(x < p->val){ //沿左子樹找
            q = p;
            p = p->lchild;   
        }
        else{   //沿右子樹找
            q = p;
            p = p->rchild;   
        }
    }
    if(p == NULL){   //沒找到
        cout << "沒有找到" << x << endl;   
    }

    if(p->lchild == NULL && p->rchild == NULL){  //p為葉子節(jié)點(diǎn)
        if(p == BT){  //p為根節(jié)點(diǎn)
            BT = NULL;   
        }
        else if(q->lchild == p){  
            q->lchild = NULL;
        }       
        else{
            q->rchild = NULL;   
        }
        free(p);  //釋放節(jié)點(diǎn)p
    }
    else if(p->lchild == NULL || p->rchild == NULL){ //p為單支子樹
        if(p == BT){  //p為根節(jié)點(diǎn)
            if(p->lchild == NULL){
                BT = p->rchild;   
            }   
            else{
                BT = p->lchild;   
            }
        }   
        else{
            if(q->lchild == p && p->lchild){ //p是q的左子樹且p有左子樹
                q->lchild = p->lchild;    //將p的左子樹鏈接到q的左指針上
            }   
            else if(q->lchild == p && p->rchild){
                q->lchild = p->rchild;   
            }
            else if(q->rchild == p && p->lchild){
                q->rchild = p->lchild;   
            }
            else{
                q->rchild = p->rchild;
            }
        }
        free(p);
    }
    else{ //p的左右子樹均不為空
        pnode t = p;
        pnode s = p->lchild;  //從p的左子節(jié)點(diǎn)開始
        while(s->rchild){  //找到p的前驅(qū)，即p左子樹中值最大的節(jié)點(diǎn)
            t = s;  
            s = s->rchild;   
        }
        p->val = s->val;   //把節(jié)點(diǎn)s的值賦給p
        if(t == p){
            p->lchild = s->lchild;   
        }   
        else{
            t->rchild = s->lchild;   
        }
        free(s);
    }
    return find;
}