创建二叉树和实现二叉树的三种遍历 a. 根据提示输入字符型数据创建二叉树，输入值为所有字符型数据 b. 输出为遍历后的每个结点的值的顺序 c. 创建二叉树并能实现二叉树的先序、中序、后序遍历 d. 如果输入数据为：a b c 输出结果为：a b c b a c b c a 程序流程：main()àclrscr()àcreatetree()àpreorder()àinorder()àpostorder

以下是 C++ 代码实现：

#include <iostream>
using namespace std;

struct TreeNode{
    char val;
    TreeNode *left;
    TreeNode *right;
    TreeNode(char x) : val(x), left(NULL), right(NULL) {}
};

void createTree(TreeNode* &root){
    char c;
    cin >> c;
    if(c == '#'){
        root = NULL;
    }
    else{
        root = new TreeNode(c);
        createTree(root->left);
        createTree(root->right);
    }
}

void preorder(TreeNode* root){
    if(root){
        cout << root->val << " ";
        preorder(root->left);
        preorder(root->right);
    }
}

void inorder(TreeNode* root){
    if(root){
        inorder(root->left);
        cout << root->val << " ";
        inorder(root->right);
    }
}

void postorder(TreeNode* root){
    if(root){
        postorder(root->left);
        postorder(root->right);
        cout << root->val << " ";
    }
}

int main(){
    cout << "Please input the characters to create a binary tree: " << endl;
    TreeNode* root;
    createTree(root);

    cout << "Preorder traversal result: ";
    preorder(root);
    cout << endl;

    cout << "Inorder traversal result: ";
    inorder(root);
    cout << endl;

    cout << "Postorder traversal result: ";
    postorder(root);
    cout << endl;

    return 0;
}

测试输入数据为 "a b # # c # #"，输出结果为：

Preorder traversal result: a b c 
Inorder traversal result: b a c 
Postorder traversal result: b c a