二叉搜索树C++实现

  1 template<typename Element>
  2 class BinarySearchTree
  3 {
  4     public:
  5         BinarySearchTree():root(NULL){}
  6         BinarySearchTree(const BinarySearchTree& bst):root(NULL)
  7         {
  8             operator=(bst);
  9         }
 10         virtual ~BinarySearchTree()
 11         { clear(root); }
 12
 13         void insert(const Element& e)
 14         { insert(root, e); }
 15         void remove(const Element& e)
 16         { remove(root, e); }
 17         bool contains(const Element& e) const
 18         { return contains(root, e); }
 19         const Element& findMin() const
 20         { return findMin(root); }
 21         const Element& findMax() const
 22         { return findMax(root); }
 23         bool isEmpty() const
 24         { return root==NULL; }
 25         void clear()
 26         { clear(root); }
 27
 28         const BinarySearchTree& operator=(const BinarySearchTree& bst)
 29         {
 30             if(this!=&bst)
 31             {
 32                 clear();
 33                 root = clone(bst.root);
 34             }
 35             return *this;
 36         }
 37
 38     private:
 39         struct BSTNode
 40         {
 41             Element element;
 42             BSTNode *left;
 43             BSTNode *right;
 44             BSTNode(const Element& e, BSTNode *lt, BSTNode *rt):
 45                 element(e), left(lt), right(rt){}
 46         };
 47         BSTNode *root;
 48
 49         BSTNode* clone(BSTNode * t)
 50         {
 51             if(t!=NULL)
 52             {
 53                 return new BSTNode(t->element, clone(t->left), clone(t->right));
 54             }
 55             return NULL;
 56         }
 57         void clear(BSTNode * &t)
 58         {
 59             if(t!=NULL)
 60             {
 61                 clear(t->left);
 62                 clear(t->right);
 63                 delete t;
 64             }
 65             t = NULL;
 66         }
 67         void insert(BSTNode * &t, const Element& e)
 68         {
 69             if(t!=NULL)
 70             {
 71                 if(e<t->element)
 72                 {
 73                     insert(t->left, e);
 74                 }
 75                 else if(e>t->element)
 76                 {
 77                     insert(t->right, e);
 78                 }
 79                 else
 80                 {
 81                 }
 82             }
 83             else
 84             {
 85                 t = new BSTNode(e, NULL, NULL);
 86             }
 87         }
 88         void remove(BSTNode * &t, const Element& e)
 89         {
 90             if(t!=NULL)
 91             {
 92                 if(e<t->element)
 93                 {
 94                     remove(t->left, e);
 95                 }
 96                 else if(e>t->element)
 97                 {
 98                     remove(t->right, e);
 99                 }
100                 else if(t->left!=NULL&&t->right!=NULL)
101                 {
102                     t->element = findMin(t->right);
103                     remove(t->right, t->element);
104                 }
105                 else
106                 {
107                     BSTNode *tmp = t;
108                     t = t->left!=NULL?t->left:t->right;
109                     delete tmp;
110                 }
111             }
112         }
113         bool contains(BSTNode * t, const Element& e) const
114         {
115             if(t!=NULL)
116             {
117                 if(e<t->element)
118                 {
119                     return contains(t->left, e);
120                 }
121                 else if(e>t->element)
122                 {
123                     return contains(t->right, e);
124                 }
125                 else
126                 {
127                     return true;
128                 }
129             }
130             else
131             {
132                 return false;
133             }
134         }
135         const Element& findMin(BSTNode* t) const
136         {
137             return t->left!=NULL?findMin(t->left):t->element;
138         }
139         const Element& findMax(BSTNode* t) const
140         {
141             return t->right!=NULL?findMax(t->right):t->element;
142         }
143 };