Mirror a Binary Tree without recursion - data-structures

Question

I am trying to mirror the binary tree without recursive methods by using two queues and a binary tree which I have created.
Following is the function which i have used.
root is the pointer to the root node of the original binary tree and mirrior_root is of a mirrored binary tree.
The error seems to be lies in the logic part !
Help would be appreciated !
#include<iostream>
#include<queue>
using namespace std;
class Node
{
public:
Node *lchild;
int data;
Node *rchild;
};
class Tree
{
public:
Node *root;
Node *mirror_root;
Tree()
{
root = NULL;
}
void create_Tree()
{
Node *p;
Node *t;
int x;
queue <Node *> q;
root = new Node ;
cout << "Enter the data you want to insert in root";
cin >> x;
root->data = x;
root->lchild = root ->rchild = NULL;
q.emplace(root);
while(! q.empty())
{
p = q.front();
q.pop();
cout << "Enter the left child of " << p->data << ":";
cin >> x;
if(x != -1)
{
t= new Node;
t->data = x;
t->lchild = t->rchild = NULL;
p->lchild = t;
q.emplace(t);
}
cout << "Enter the right child of " << p->data << ":";
cin >> x;
if(x != -1)
{
t= new Node;
t->data = x;
t->lchild = t->rchild = NULL;
p->rchild = t;
q.emplace(t);
}
}
}
void Preorder(Node *p)
{
if(p)
{
cout << p->data << " " ;
Preorder(p->lchild);
Preorder(p->rchild);
}
}
void Level_order(Node *p)
{
queue <Node *> q;
q.emplace(p);
cout << p->data << " " ;
while(!q.empty())
{
p = q.front();
q.pop();
if(p->lchild)
{
cout << p->lchild->data << " ";
q.emplace(p->lchild);
}
if(p->rchild)
{
cout << p->rchild->data << " ";
q.emplace(p->rchild);
}
}
}
void mirror_tree(Node *p)
{
Node *mirror_root;
Node *t;
Node *k;
queue <Node *> q_root;
queue <Node *> q_mirror;
mirror_root = new Node;
mirror_root->data = p->data;
mirror_root->lchild = mirror_root->rchild = NULL;
t=mirror_root;
q_root.emplace(p);
q_mirror.emplace(t);
while(!q_root.empty())
{
p=q_root.front();
q_root.pop();
t = q_mirror.front();
q_mirror.pop();
if(p->lchild)
{
k = new Node;
k->data = p->lchild->data;
k->lchild = k->rchild = NULL;
t->rchild = k;
q_root.emplace(p->lchild);
q_mirror.emplace(t->rchild);
}
if(p->rchild)
{
k = new Node;
k->data = p->rchild ->data;
k->lchild = k->rchild = NULL;
t->lchild = k;
q_root.emplace(p->rchild);
q_mirror.emplace(t->lchild);
}
}
}
};
int main()
{
Tree bt;
bt.create_Tree();
bt.mirror_tree(bt.root);
cout << "Level order of mirrored binary tree is : ";
bt.Level_order(bt.mirror_root);
}
Here is input and output
Enter the data you want to insert in root: 5
Enter the left child of 5:6
Enter the right child of 5:7
Enter the left child of 6:8
Enter the right child of 6:9
Enter the left child of 7:10
Enter the right child of 7:11
Enter the left child of 8:-1
Enter the right child of 8:-1
Enter the left child of 9:-1
Enter the right child of 9:-1
Enter the left child of 10:-1
Enter the right child of 10:-1
Enter the left child of 11:-1
Enter the right child of 11:-1
Level order of mirrored binary tree is : 7769539
Output which i expected is
Level order of mirrored binary tree is 5 7 6 11 10 9 8

Answer 1

The problem is that you declare Node *mirror_root as a local variable in mirror_tree, while you want the code to give a value to the class member with the same name.
So remove that line from the mirror_tree function.