Question

write pseudocode for an iterative implementation of a function for counting the number of nodes in a BST using a stack to visit in Depth First Search the nodes of the tree. Pseudocode must be code like and describe every necessary step.

Language: C++

Answer 1

The pseudo code with proper comments is as below:

#include <bits/stdc++.h>
using namespace std;
  
// There is a pointer to left child and right child in binary tree
struct Node
{
int data;
struct Node* left, *right;
};
  
// We can get the count of full nodes
unsigned int getwholeCount(struct Node* node)
{
// when the tree is empty
if (!node)
return 0;
queue<Node *> q;
  
//starting from the root doing level order traversal
int count = 0; // Initializing the count of full nodes
q.push(node);
while (!q.empty())
{
struct Node *temp = q.front();
q.pop();
  
if (temp->left && temp->right)
count++;
  
if (temp->left != NULL)
q.push(temp->left);
if (temp->right != NULL)
q.push(temp->right);
}
return count;
}
  
//Function helping to allocate a new node with data
struct Node* newNode(int data)
{
struct Node* node = new Node;
node->data = data;
node->left = node->right = NULL;
return (node);
}
  
// Driver program
int main(void)
{
/* 3
/ \
6 4
\ \
7 10
/ \ /
2 12 4
Creating the above Binary Tree
*/
  
struct Node *root = newNode(3);
root->left = newNode(6);
root->right = newNode(4);
root->left->right = newNode(7);
root->left->right->left = newNode(2);
root->left->right->right = newNode(12);
root->right->right = newNode(10);
root->right->right->left = newNode(4);
  
cout << getwholeCount(root);
  
return 0;
}