class BST{
public: struct Node {
int key;
//节点的key int value;
//节点的value Node* left;
Node *right;
int N;
//节点的叶子节点数目 Node(int _key, int _value, int _N) {
key = _key;
value = _value;
N = _N;
}
}
;
BST();
~BST();
void put(int key, int value);
int get(int key);
int deleteKey(int key);
private: Node* _deleteKey(int key, Node *x);
Node* _deleteMin(Node *x);
int size(Node *x);
int _get(int key, Node* x);
Node * _put(int key, int value,Node *x);
Node * min(Node *x);
Node* root;
}
;
inline int BST::size(Node * x){
if (x == nullptr)return 0;
return x->N;
}
int BST::_get(int key, Node * x){
if (x == nullptr)return 0;
if (x->key < key)_get(key, x->right);
else if (x->key > key)_get(key, x->left);
else {
return x->value;
}
return 0;
}
BST::Node* BST::_put(int key, int value, Node * x){
if (x == nullptr) {
Node *tmp = new Node(key, value, 1);
return tmp;
}
if (x->key > key) {
x->left=_put(key, value, x->left);
}
else if (x->key < key) {
x->right=_put(key, value, x->right);
}
else x->key = key;
x->N = size(x->left) + size(x->right) + 1;
return x;
}
BST::Node* BST::min(Node * x){
if (x->left == nullptr)return x;
return min(x->left);
}
BST::BST(){
}
BST::~BST(){
}
void BST::put(int key, int value){
root=_put(key, value, root);
}
int BST::get(int key){
return _get(key, root);
}
BST::Node* BST::_deleteKey(int key, Node * x){
if (x->key > key)x->left = _deleteKey(key, x->left);
else if (x->key < key)x->right = _deleteKey(key, x->right);
else {
if (x->left == nullptr)return x->right;
else if (x->right == nullptr)return x->left;
else {
Node *tmp = x;
x = min(tmp->right);
x->left = tmp->left;
x->right = _deleteMin(tmp->right);
}
}
x->N = size(x->left) + size(x->right) + 1;
return x;
}
BST::Node* BST::_deleteMin(Node * x){
if (x->left == nullptr)return x->right;
x->left = _deleteMin(x->left);
x->N = size(x->left) + size(x->right) + 1;
return x;
}
int BST::deleteKey(int key){
return _get(key, root);
}