二叉树的四种遍历方式（前序遍历，中序遍历，后序遍历，层序遍历）C++语言

/**
 *作者：魏宝航
 *2020年11月27日,下午15:08
 */
#include<iostream>
#include<vector>
#include<queue>
using namespace std;
class Node {
public:
    char ch;
    Node* left;
    Node* right;
    Node() {
        ch = '\0';
        left = NULL;
        right = NULL;
    }
    Node(char ch, Node* left, Node* right) {
        this->ch = ch;
        this->left = left;
        this->right = right;
    }
};
static int i = 0;
//#号法创建二叉树
Node* CreateTree(vector<char> arr,Node* root) {
    if (i < arr.size()) {
        char temp = arr[i++];
        if (temp == '#') {
            return NULL;
        }
        else {
            root = new Node();
            root->ch = temp;
            root->left = CreateTree(arr, root->left);
            root->right = CreateTree(arr, root->right);
        }
    }
    return root;
}
//二叉树的前序遍历
void preOrder(Node* root) {
    if (root == NULL) {
        return;
    }
    cout << root->ch << " ";
    preOrder(root->left);
    preOrder(root->right);
}
//二叉树的中序遍历
void midOrder(Node* root) {
    if (root == NULL) {
        return;
    }
    midOrder(root->left);
    cout << root->ch << " ";
    midOrder(root->right);
}
//二叉树的后序遍历
void postOrder(Node* root) {
    if (root == NULL) {
        return;
    }
    postOrder(root->left);
    postOrder(root->right);
    cout << root->ch << " ";
}
//二叉树的层序遍历
void levelOrder(Node* root) {
    queue<Node*> q;
    q.push(root);
    while (!q.empty()) {
        Node* temp = q.front();
        cout << temp->ch << " ";
        q.pop();
        if (temp->left != NULL) {
            q.push(temp->left);
        }
        if (temp->right != NULL) {
            q.push(temp->right);
        }
    }
}
int main() {
    vector<char> v;
    char arr[] = { 'A','B','D','#','#','E','#','#','C','#','F','#','#' };
    char arr1[] = { '#' };
    for (int i = 0; i < 13; i++) {
        v.push_back(arr[i]);
    }
    Node* root=new Node();
    root=CreateTree(v,root);
    preOrder(root);
    midOrder(root);
    postOrder(root);
    levelOrder(root);
}