二叉树的非递归遍历c++实现（与递归进行了对比）

 1 #include<iostream>
 2 #include<stack>
 3 using namespace std;
 4 
 5 const int My_False = 0;  //或者采用宏：#define My_False 0;这里参考Effective c++ 做法
 6 const int My_True = 1;
 7 
 8 //二叉树原始节点
 9 struct BinaryNode
10 {
11     char ch;
12     BinaryNode* lchild;
13     BinaryNode* rchild;
14 };
15 //封装了flag的节点
16 struct BiTreeStackNode
17 {
18     BinaryNode* root;
19     int flag;
20 };
21 //创建封装后栈中的节点
22 BiTreeStackNode* CreateBiTreeStackNode(BinaryNode* node, int flag) {
23     BiTreeStackNode* newnode = new BiTreeStackNode;
24     newnode->root = node;
25     newnode->flag = flag;
26     return newnode;
27 }
28 //非递归遍历
29 void NonRecursion(BinaryNode* root) {
30     //创建栈
31     stack<BiTreeStackNode*> stack;
32     //把当前封装后节点入栈
33     stack.push(CreateBiTreeStackNode(root, My_False));
34     while (!stack.empty()) {
35         //先弹出栈顶元素
36         BiTreeStackNode* node = stack.top();
37         stack.pop();
38         //判断弹出的节点是否为空
39         if (node->root == NULL) continue;
40         if (node->flag == My_True) cout << node->root->ch<<" ";
41         else
42         {
43             //当前封装后节点中原始节点的右节点入栈
44             stack.push(CreateBiTreeStackNode(node->root->rchild, My_False));
45             //当前封装后节点中原始节点的左节点入栈
46             stack.push(CreateBiTreeStackNode(node->root->lchild, My_False));
47             //将当前节点的flag改为My_True并重新压栈
48             node->flag = My_True;
49             stack.push(node);
50         }
51     }
52 }
53 //递归遍历
54 void Recursion(BinaryNode* root) {
55     if (!root) return;
56 
57     cout << root->ch << " ";
58     Recursion(root->lchild);
59     Recursion(root->rchild);
60 }
61 //初始化二叉树
62 void CreateBinaryTree() {
63     BinaryNode node1 = { 'A',NULL,NULL };
64     BinaryNode node2 = { 'B',NULL,NULL };
65     BinaryNode node3 = { 'C',NULL,NULL };
66     BinaryNode node4 = { 'D',NULL,NULL };
67     BinaryNode node5 = { 'E',NULL,NULL };
68     BinaryNode node6 = { 'F',NULL,NULL };
69     BinaryNode node7 = { 'G',NULL,NULL };
70     BinaryNode node8 = { 'H',NULL,NULL };
71     //建立节点关系
72     node1.lchild = &node2;
73     node1.rchild = &node6;
74     node2.rchild = &node3;
75     node3.lchild = &node4;
76     node3.rchild = &node5;
77     node6.rchild = &node7;
78     node7.lchild = &node8;
79     //二叉树的非递归打印
80     cout << "二叉非树递归遍历：n";
81     NonRecursion(&node1);
82     cout << endl<<"二叉树递归遍历：n";
83     Recursion(&node1);
84 }
85 
86 int main() {
87     CreateBinaryTree();
88 }