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Code Binary Tree

Inorder traversal of binary tree using stack in c++

C++ program for Inorder traversal of binary tree using stack. Here problem description and explanation.

``````// Include header file
#include <iostream>

using namespace std;
// C++ program for
// Inorder traversal without recursion
// Using stack

// Binary Tree node
class TreeNode
{
public: int data;
TreeNode *left;
TreeNode *right;
// Make a tree node
TreeNode(int data)
{
// Set node data
this->data = data;
this->left = nullptr;
this->right = nullptr;
}
};
class StackNode
{
public: TreeNode *element;
StackNode *next;
StackNode(TreeNode *element)
{
this->element = element;
this->next = nullptr;
}
};
// Stack Class
class MyStack
{
public:
StackNode *top;
int size;
MyStack()
{
this->top = nullptr;
this->size = 0;
}
// Add new element into stack
void push(TreeNode *element)
{
// Create new node
StackNode *node = new StackNode(element);
node->next = this->top;
// new node is new top
this->top = node;
// Increase the size
this->size += 1;
}
// Remove top element of the stack
void pop()
{
if (this->top != nullptr)
{
// next node is new top
this->top = this->top->next;
// Reduce size
this->size -= 1;
}
}
// Returns the status of empty or non empty stacks
bool isEmpty()
{
if (this->size > 0 && this->top != nullptr)
{
return false;
}
else
{
return true;
}
}
TreeNode *peek()
{
if (this->isEmpty())
{
return nullptr;
}
return this->top->element;
}
};
class BinaryTree
{
public: TreeNode *root;
BinaryTree()
{
this->root = nullptr;
}
// Display Inorder view of binary tree
void inorder()
{
if (this->root != nullptr)
{
// Make new stack
MyStack *s = new MyStack();
TreeNode *node = this->root;
// Display tree element
while (!s->isEmpty() || node != nullptr)
{
if (node != nullptr)
{
s->push(node);
// Visit to left subtree
node = node->left;
}
else
{
// When node is null
// Get stack top element
node = s->peek();
// Display node value
cout << " " << node->data;
// Remove top element of the stack
s->pop();
// Visit to left subtree of current node
node = node->right;
}
}
}
else
{
}
}
};
int main()
{
// Create new tree
BinaryTree *tree = new BinaryTree();
/*
Construct Binary Tree
-----------------------
15
/  \
24   54
/    /  \
35   62   13
*/
tree->root = new TreeNode(15);
tree->root->left = new TreeNode(24);
tree->root->right = new TreeNode(54);
tree->root->right->right = new TreeNode(13);
tree->root->right->left = new TreeNode(62);
tree->root->left->left = new TreeNode(35);
// Display result
tree->inorder();
return 0;
}``````

Output

`` 35 24 15 62 54 13``

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