Preorder Tree Traversal in Binary Tree In C++

March 3, 2023

Preorder Tree Traversal

Preorder traversal is a depth first algorithm. There are three types of traversals in tree: Preorder, Inorder, Postorder. In this article, preorder tree traversal is performed using recursion.

More About Preorder Traversal

We first print the value of the node,them move to the left subtree and finally to the right subtree.
If we need to explore more about the node itself before inspecting its leaves, we use preorder traversal.
Preorder traversal is used to find the prefix expression of an expression tree.

Steps To Find Preorder Traversal:

Print the root node and traverse the left subtree.
After printing 12, move to the left.
8 is printed and we move to the left subtree.
Print 5 and move back,
Since there is only 1 right child 13 is printed and we move to the right subtree.
54 and 18 are printed.

Trees in Data Structure(Introduction)

Types of Trees in data structure

Inorder Postorder Preorder Traversal Examples

Inorder Tree Traversal in Binary Tree

Postorder Tree Traversal in Binary Tree

Algorithm To Find Preorder Traversal:

If root is NULL, return NULL.
Print the node.
Visit left subtree.
Visit right subtree.

Code Implementation for Preorder Tree traversal

Run

#include<bits/stdc++.h>
using namespace std;
class Tree
{
public:
  int data;
  Tree *left = NULL, *right = NULL;
  // Constructor initialised
    Tree (int x)
  {
    data = x;
    left = NULL;
    right = NULL;
  }
};
void preorder_traversal (Tree * root)
{
  if (root == NULL)
    return;
  // Print the data
  cout << root->data << " ";
  // Visit Left subtree
  preorder_traversal (root->left);
  // Visit right subtree
  preorder_traversal (root->right);
}

int main ()
{
  Tree *root = new Tree (15);
  root->left = new Tree (12);
  root->right = new Tree (54);
  root->left->left = new Tree (8);
  root->left->right = new Tree (13);
  root->left->left->left = new Tree (5);
  root->right->left = new Tree (18);
  preorder_traversal (root);
  return 0;
}

Output:

15 12 8 5 13 54 18

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Introduction to Trees

Binary Trees

Binary Tree in Data Structures (Introduction)
Tree Traversals: Inorder Postorder Preorder : C | C++ | Java
Inorder Postorder PreOrder Traversals Examples
- Inorder Tree Traversal in Binary Tree: C | C++ | Java
- Preorder Tree Traversal in Binary Tree : C | C++ | Java
- Postorder Tree Traversal in Binary Tree : C | C++ | Java
Tree Traversal without Recursion
- Postorder Preorder Inorder Traversal without recursion
- Inorder Tree Traversal without Recursion – C | C++ | Java
- Preorder Tree Traversal without Recursion – C | C++ | Java
- Postorder Tree Traversal without Recursion – C | C++ | Java

Binary Search Trees

Binary search tree in Data Structures (Introduction)
- BST: Introduction to Binary Search Tree
- BST: Binary Search Tree Program : C | C++ | Java
- BST: Search a node in Binary Search Tree : C | C++ | Java
- BST: Insertion in a Binary Search Tree : C | C++ | Java
- BST: Deletion in a Binary Search Tree : C | C++ | Java

Traversals

Traversal in Trees
Tree Traversals: Breadth-First Search (BFS) : C | C++ | Java
Tree Traversals: Depth First Search (DFS) : C | C++ | Java
Construct a Binary Tree from Postorder and Inorder

B – Trees

B-Tree
- B-Tree: Introduction
- B-Tree: Insertion : C | C++ | Java
- B-Tree: Deletion : C | C++ | Java

AVL Trees

AVL Trees
- AVL Trees: Introduction
- AVL Tree Insertion : C | C++ | Java
- AVL Tree Deletion : C | C++ | Java
- Insertion in a Binary Tree (Level Order) – C | C++ | Java
- Searching in Binary Tree – C | C++ | Java
- Searching in a Binary Search Tree – C | C++ | Java

Complete Programs for Trees

Depth First Traversals – C | C++ | Java
Level Order Traversal – C | C++ | Java
Construct Tree from given Inorder and Preorder traversals – C | C++ | Java
Construct Tree from given Postorder and Inorder traversals – C | C++ | Java
Construct Tree from given Postorder and Preorder traversal – C | C++ | Java
Find size of the Binary tree – C | C++ | Java
Find the height of binary tree – C | C++ | Java
Find maximum in binary tree – C | C++ | Java
Check whether two tree are identical- C| C++| Java
Spiral Order traversal of Tree- C | C++| Java
Level Order Traversal Line by Line – C | C++| Java
Hand shaking lemma and some Impotant Tree Properties.
Check If binary tree if Foldable or not.- C| C++| Java
check whether tree is Symmetric – C| C++| Java.
Check for Children-Sum in Binary Tree- C|C++| Java
Sum of all nodes in Binary Tree- C | C++ | Java
Lowest Common Ancestor in Binary Tree- C | C++ | Java