二叉树的镜像

#include <iostream>
using namespace std;

struct tree
{
    double data;
    struct tree *left,*right;
    tree(int d=0):data(d)
    {
        left=right=nullptr;
    }
};
class Solution
{
    public:
        void create(tree *&root);
        void pre_order(tree *root);
        void mirror(tree *r); 
        tree *root;    
};
void Solution::create(tree *&root)
{
    double x;
    cin>>x;
    if(x==0)
        root=nullptr;
    else
    {
        root=new tree();
        root->data=x;
        create(root->left);
        create(root->right);
    }
}
void Solution::pre_order(tree *root)
{
    if(root)
    {
        cout<<root->data<<endl;
        pre_order(root->left);
        pre_order(root->right);
    }
}
void Solution::mirror(tree *r)
{
    if(!r)
        return;
    if(r->left==nullptr&&r->right==nullptr)
        return;
    auto t=r->left;
    r->left=r->right;
    r->right=t;
    
    if(r->left)
        mirror(r->left);
    if(r->right)
        mirror(r->right); 
}
int main()
{
    Solution s;
    s.create(s.root);
    s.mirror(s.root);
    s.pre_order(s.root);
    return 0;
}