二叉查找树-优化版，使用了指针引用

  1 //与上一次实现不同，这里使用了大量的指针引用，
  2 //因此节省了一个指向父节点的指针
  3 #include<iostream>
  4 #include<vector>
  5 #include<ctime>
  6 #include<cstdlib>
  7 
  8 using namespace std;
  9 
 10 template<class T>
 11 class BinarySearchTree
 12 {
 13     private:
 14         struct Node
 15         {
 16             T data;
 17             Node *left;
 18             Node *right;
 19             Node(T val)
 20             {
 21                 data = val;
 22                 left = NULL;
 23                 right = NULL;
 24             }
 25 
 26             private:
 27             Node() 
 28             {
 29             }
 30         };
 31         Node *root;
 32         int size;
 33 
 34     public:
 35         BinarySearchTree()
 36         {
 37             root = NULL;
 38             size = 0;
 39         }
 40         ~BinarySearchTree()
 41         {
 42             clear(root);
 43             root = NULL;
 44             size = 0;
 45         }
 46         Node*& findMin(Node *&node) const
 47         {
 48             if(node->left == NULL)
 49                 return node;
 50             else
 51                 return findMin(node->left);
 52         }
 53         T max(Node *node) const
 54         {
 55             if(node->right == NULL)
 56                 return node->data;
 57             else
 58                 return max(node->right);
 59         }
 60 
 61         Node *& insert(Node *& node,T val)
 62         {
 63             if(node == NULL)
 64             {
 65                 node = new Node(val);
 66                 size++; 
 67                 return node;
 68             }
 69             if(val > node->data)
 70                 return insert(node->right,val);
 71             else if(val < node->data)
 72                 return insert(node->left,val);
 73             else
 74                 return node;
 75         }
 76 
 77         bool contain(Node *& node,T val) const
 78         {
 79             if(node == NULL)
 80                 return false;
 81 
 82             if(val > node->data)
 83                 return contain(node->right,val);
 84             else if(val < node->data)
 85                 return contain(node->left,val);
 86             else
 87                 return true;
 88         }
 89 
 90         void remove(Node* &node,T val)
 91         {
 92             if(node == NULL)
 93             {
 94                 cout<<"remove() error!\n";
 95                 return;
 96             }
 97             if(val > node->data)
 98                 remove(node->right,val);
 99             else if(val < node->data)
100                 remove(node->left,val);
101             else if(val == node->data)
102             {
103                 if(node->left == NULL && node->right == NULL)
104                 {
105                     delete node;
106                     node = NULL;
107                 }
108                 else if(node->left == NULL && node->right != NULL)
109                 {
110                     Node *p = node;
111                     node = node->right;
112                     delete p;
113                     size--;
114                 }
115                 else if(node->left != NULL && node->right == NULL)
116                 {
117                     Node *p = node;
118                     node = node->left;
119                     delete p;
120                     size--;
121                 }
122                 else if(node->left != NULL && node->right != NULL)
123                 {
124                     Node* &p = findMin(node->right);
125                        node->data = p->data;
126                     p = p->right;
127                     delete p;
128                     size--;    
129                 }
130             }
131         }
132         void clear(Node* &node)
133         {
134             if(node->left != NULL)
135                 clear(node->left);
136             if(node->right != NULL)
137                 clear(node->right);
138 
139             delete node;
140             node = NULL;
141         }
142         void print(Node *node)
143         {
144             if(node == NULL)
145                 return;
146             cout<<node->data<< " ";
147             if(node->left != NULL)
148                 print(node->left);
149             if(node->right != NULL)
150                 print(node->right);
151         }
152         void insert(T val)
153         {
154             insert(root,val);
155         }
156         void remove(T val)
157         {
158             remove(root,val);
159         }
160         void print()
161         {
162             print(root);
163             cout<<"\n";
164         }
165 };
166 
167 int main()
168 {
169     BinarySearchTree<int> tree;
170     tree.insert(10);
171     tree.insert(1);
172     tree.insert(11);
173     tree.insert(9);
174     tree.insert(8);
175     tree.print();
176     cout<<"\n\n";
177     tree.remove(9);
178     tree.print();
179 
180     return 0;
181 }