Print all leaf nodes of a binary tree from right to left in C++

In this problem, we are given a binary tree and we have to print all leaf nodes of the binary tree from right to left.
Let’s take an example to understand the problem
Input −
Output − 7 4 1
To solve this problem, we will have to traverse the binary tree. This traversal can be done in two ways −
Preorder traversal − This traversal uses recursion. Here, we will traverse, root then left and then right subtree. If we encounter a leaf node then we will print it, else we check for children of the node and explore them to find leaf node.
Program to show the implementation of our solution −
 Live Demo
#include <iostream>
using namespace std;
struct Node {
   int data;
   struct Node *left, *right;
};
Node* insertNode(int data) {
   Node* temp = new Node;
   temp->data = data;
   temp->left = temp->right = NULL;
   return temp;
}
void findLeafNode(Node* root) {
   if (!root)
      return;
   if (!root->left && !root->right) {
      cout<<root->data<<"\t";
      return;
   }
   if (root->right)
      findLeafNode(root->right);
   if (root->left)
      findLeafNode(root->left);
}
int main() {
   Node* root = insertNode(21);
   root->left = insertNode(5);
   root->right = insertNode(11);
   root->left->left = insertNode(8);
   root->left->right = insertNode(98);
   root->right->left = insertNode(2);
   root->right->right = insertNode(8);
   cout<<"Leaf nodes of the tree from right to left are:\n";
   findLeafNode(root);
   return 0;
}
Leaf nodes of the tree from right to left are −
18 2 98 8
Postorder Traversal − This traversal to find the leaf node will use iteration. We will use a stack to store data and traverse the tree in a postorder manner (first right subtree then left subtree and then root) and print leaf nodes.
Program to show the implementation of our solution −
 Live Demo
#include<bits/stdc++.h>
using namespace std;
struct Node {
   Node* left;
   Node* right;
   int data;
};
Node* insertNode(int key) {
   Node* node = new Node();
   node->left = node->right = NULL;
   node->data = key;
   return node;
}
void findLeafNode(Node* tree) {
   stack<Node*> treeStack;
   while (1) {
      if (tree) {
         treeStack.push(tree);
         tree = tree->right;
      } else {
         if (treeStack.empty())
            break;
         else {
            if (treeStack.top()->left == NULL) {
               tree = treeStack.top();
               treeStack.pop();
               if (tree->right == NULL)
                  cout<<tree->data<<"\t";
            }
            while (tree == treeStack.top()->left) {
               tree = treeStack.top();
               treeStack.pop();
               if (treeStack.empty())
                  break;
            }
            if (!treeStack.empty())
               tree = treeStack.top()->left;
            else
               tree = NULL;
         }  
      }
   }
}
int main(){
   Node* root = insertNode(21);
   root->left = insertNode(5);
   root->right = insertNode(11);
   root->left->left = insertNode(8);
   root->left->right = insertNode(98);
   root->right->left = insertNode(2);
   root->right->right = insertNode(18);
   cout<<"Leaf nodes of the tree from right to left are:\n";
   findLeafNode(root);
   return 0;
}
Leaf nodes of the tree from right to left are −
18 2 98 8