简单用c++实现二叉树的一部分：
1 #include <iostream> 2 #include<queue> 3 4 #define null NULL 5 6 7 //定义二叉树类 8 template <typename Entry> 9 class binary_tree 10 { 11 protected: 12 //定义树结点,方便访问，不封装，全部开放 13 struct binary_node 14 { 15 Entry data; //数据域 16 binary_node* left; //指向左子树的指针域 17 binary_node* right; //指向右子树的指针域 18 binary_node(){} //无参数构造函数 19 binary_node(const Entry& x):data(x),right(null),left(null){} //带参数构造函数 20 }; 21 22 binary_node* root; //指向根结点的指针 23 24 public: 25 binary_tree(); 26 binary_tree(const binary_tree& bt); 27 virtual ~binary_tree(); 28 bool empty() const; 29 int size() const; 30 int height() const; 31 void clear(); 32 void preorder(binary_node*root,void(*visit)(Entry&)); 33 void inorder(binary_node*root,void(*visit)(Entry&)); 34 void postorder(binary_node*root,void(*visit)(Entry&)); 35 void level_traversal(binary_node*root,void(*visit)(Entry&)) 36 int insert(const Entry&); 37 int remove(const Entry&); 38 binary_tree& operator=(const binary_tree& bt); 39 40 }; 41 42 43 44 template <typename Entry> 45 binary_tree<Entry>::binary_tree():root(null){} 46 47 template <typename Entry> 48 bool binary_tree<Entry>::empty() const 49 { 50 return (root == null); 51 } 52 53 54 //用前序遍历来获得结点的数目 55 template <typename Entry> 56 int binary_tree<Entry>::size() const 57 { 58 stack<binary_node*> s; 59 int size = 0; 60 binary_node* p = root; 61 while(p!=null || !s.empty()) 62 { 63 while(p != null) 64 { 65 size++; 66 s.push(p); 67 p = p->left; 68 } 69 70 if(!s.empty()) 71 { 72 p = s.top(); 73 s.pop(); 74 p = p->right; 75 } 76 } 77 return size; 78 79 } 80 81 82 template <typename Entry> 83 void binary_tree<Entry>::visit(Entry& a) 84 { 85 cout<<"current data is: "<<a<<endl; 86 } 87 88 //先序遍历 89 template <typename Entry> 90 void binary_tree<Entry>::preorder(binary_node root,void (*visit)(Entry& bt)) 91 { 92 if(root != null) 93 { 94 (*visit)(root->data); 95 preorder(root->left,visit); 96 preorder(root->right,visit); 97 } 98 } 99 100 //中序遍历 101 template <typename Entry> 102 void binary_tree<Entry>::inorder(binary_node root,void (*visit)(Entry& bt)) 103 { 104 if(root != null) 105 { 106 preorder(root->left,visit); 107 (*visit)(root->data); 108 preorder(root->right,visit); 109 } 110 } 111 112 //后序遍历 113 template <typename Entry> 114 void binary_tree<Entry>::postorder(binary_node *root,void (*visit)(Entry& bt)) 115 { 116 if(root != null) 117 { 118 preorder(root->left,visit); 119 preorder(root->right,visit); 120 (*visit)(root->data); 121 } 122 } 123 124 //利用队列层次遍历 125 template <typename Entry> 126 void binary_tree<Entry>::level_traversal(binary_node *root,void (*visit)(Entry&)) 127 { 128 queue<binary_node*> q; 129 if(root != null) 130 q.push(root); 131 while(!q.empty()) 132 { 133 (*visit)(q.front()->data); 134 if(q.front()->left) 135 q.push(q.front()->left); 136 if(q.front()->right) 137 q.push(q.front()->right); 138 q.pop(); 139 } 140 }