Deepest left leaf node in a binary tree in C++

In this tutorial, we are going to find the deepest left leaf node in the binary tree. Let's see the binary tree.

   A
      B    C
D       E       F
                     G

Let's see the steps to solve the problem.

Write a Node struct with char, left, and right pointers.
Initialize the binary tree with dummy data.
Write a recursive function to find the deepest left node in the binary function. It takes three argument root node, isLeftNode, and result pointer to store the deepest node.
If the current node is left and is leaf node, then update the result node with current node.
Call the recursive function on left sub tree.
Call the recursive function on right sub tree.
If the result node is null, then there is no node that satisfies our conditions.
Else print the data in the result node.

Example

Let's see the code.

Live Demo

#include <bits/stdc++.h>
using namespace std;
struct Node {
   char data;
   struct Node *left, *right;
};
Node *addNewNode(char data) {
   Node *newNode = new Node;
   newNode->data = data;
   newNode->left = newNode->right = NULL;
   return newNode;
}
void getDeepestLeftLeafNode(Node *root, bool isLeftNode, Node **resultPointer) {
   if (root == NULL) {
      return;
   }
   if (isLeftNode && !root->left && !root->right) {
      *resultPointer = root;
      return;
   }
   getDeepestLeftLeafNode(root->left, true, resultPointer);
   getDeepestLeftLeafNode(root->right, false, resultPointer);
}
int main() {
   Node* root = addNewNode('A');
   root->left = addNewNode('B');
   root->right = addNewNode('C');
   root->left->left = addNewNode('D');
   root->right->left = addNewNode('E');
   root->right->right = addNewNode('F');
   root->right->left->right = addNewNode('G');
   Node *result = NULL;
   getDeepestLeftLeafNode(root, false, &result);
   if (result) {
      cout << "The deepest left child is " << result->data << endl;
   }
   else {
      cout << "There is no left leaf in the given tree" << endl;
   }
   return 0;
}