基于二叉链表的二叉树的遍历

#include <iostream>
using namespace std;
typedef struct TreeNode{
    char val;
    TreeNode* left;
    TreeNode* right;
    TreeNode():val(0),left(nullptr),right(nullptr){};
    TreeNode(int x):val(x),left(nullptr),right(nullptr){};
}TreeNode,*BiTree;

BiTree PreInsertBiTree(){
    char x;
    cin>>x;
    if(x == '0') return nullptr;
    TreeNode* root = new TreeNode (x);
    root->left = PreInsertBiTree();
    root->right = PreInsertBiTree();

    return root;
}
void PreOrder(BiTree B){
    if(B == nullptr || B->val == '0') return ;
    cout<<B->val;
    PreOrder(B->left);
    PreOrder(B->right);
}
void InOrder(BiTree B){
    if(B == nullptr || B->val == '0') return;
    InOrder(B->left);
    cout<<B->val;
    InOrder(B->right);
}
void PostOrder(BiTree B){
    if(B == nullptr || B->val == '0') return ;
    PostOrder(B->left);
    PostOrder(B->right);
    cout<<B->val;
}

void DeleteTree(BiTree B){
    if(B == nullptr) return ;
    DeleteTree(B->left);
    DeleteTree(B->right);
    delete B;
}
int main(){


    BiTree B;
    do {
        B = PreInsertBiTree();
        if (B != nullptr) {  // 确保B不是空的
            PreOrder(B);
            cout << endl;
            InOrder(B);
            cout << endl;
            PostOrder(B);
            cout << endl;
        }
        DeleteTree(B);  // 删除旧的二叉树
    } while (B != nullptr && B->val != '0');  // 修改循环条件

    return 0;
}