Mirror a binary tree, C++ (gcc)

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#include <iostream>
#include <list>
#include <vector>
using namespace std;

struct BinTree {
  
    int data;
    BinTree *left;
    BinTree *right;
    
    BinTree(int d, BinTree* l, BinTree* r): data(d), left(l), right(r) {}
};

void mirrorTree(BinTree* root) {
    if (!root)
        return;

mirrorTree(root->left);
    mirrorTree(root->right);
    
    swap(root->left, root->right);
}

void printInorder(BinTree* root) {
    
    if (!root)
        return;
    
    printInorder(root->left);
    cout << root->data << " ";
    printInorder(root->right);
}

//           4
//         /   \
//        2     8   
//       / \   / \   
//      1  3  6   9
//           / \
//          5   7

int main()
{
    BinTree *h = new BinTree(7, NULL, NULL);
    BinTree *j = new BinTree(5, NULL, NULL);
    BinTree *g = new BinTree(9, NULL, NULL);
    BinTree *f = new BinTree(6, j, h);
    BinTree *e = new BinTree(3, NULL, NULL);
    BinTree *d = new BinTree(1, NULL, NULL);
    BinTree *c = new BinTree(8, f, g);
    BinTree *b = new BinTree(2, d, e);
    BinTree *a = new BinTree(4, b, c);
    
    printInorder(a); cout << endl;
    mirrorTree(a);
    printInorder(a); cout << endl;
    
}

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Compilation time: 0.45 sec, absolute running time: 0.15 sec, cpu time: 0 sec, memory peak: 3 Mb, absolute service time: 0.61 sec