Level Order Traversal in C Language

April 8, 2023

Level Order Traversal

On his page we will discuss about level order traversal in C language . Level order traversal is a way of traversing a binary tree where we visit all the nodes at each level of the tree before moving on to the next level. This can be accomplished using a queue data structure .

Level Order Traversal In c

Level Order Traversal In C

Level order traversal, also known as breadth-first traversal, is a method used to traverse a binary tree in C (or any other programming language) in a breadth-wise manner, level by level, from the root node to the leaf nodes

Level Order Traversal in C

Steps for Level Order Traversal

  • Step 1 : Push the root i.e. 50 to the queue.
  • Step 2 : Pop the element 50 from the queue and print it.
  • Step 3 : Now, Add it’s left and right child i.e. add 30 and 70 to queue.
  • Step 4 : Again pop the front element i.e. 30 from queue and print it .
  • Step 5 :  Add it’s left and right child i.e. 10 and 40 in the queue.
  • Step 6 : Pop the element 70 from the queue and  print it.
  • Step 7 : add it’s left and right child i.e. 60 and 90.
  • Step 8 : Now pop all the elements from the queue and print them as there is no child of these elements.
      Therefore the printing sequence will be 50 30 70 10 40 60 90 .

Algorithm

  1. If the root is NULL, return.
  2. Otherwise push the root in queue.
  3. Pop the node from the queue.
  4. Print the node’s data and add its left and right child.
  5. Repeat until the queue is empty.
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Implementation of Level Order Traversal In C

Run 
#include <stdio.h>
#include <stdlib.h>

struct Node
{
  int data;
  struct Node *left;
  struct Node *right;
};

struct Node *createNode (int data)
{
  struct Node *newNode = (struct Node *) malloc (sizeof (struct Node));
  newNode->data = data;
  newNode->left = NULL;
  newNode->right = NULL;
  return newNode;
}

void levelOrderTraversal (struct Node *root)
{
  if (root == NULL)
    return;

  // create a queue and enqueue the root node
  struct Node **queue =
    (struct Node **) malloc (sizeof (struct Node *) * 100);
  int front = 0, rear = 0;
  queue[rear++] = root;

  while (front < rear)
    {
      // dequeue a node from the queue
      struct Node *current = queue[front++];

      // process current node
      printf ("%d ", current->data);

      // enqueue the left child
      if (current->left != NULL)
	{
	  queue[rear++] = current->left;
	}

      // enqueue the right child
      if (current->right != NULL)
	{
	  queue[rear++] = current->right;
	}
    }
}

int main ()
{
  struct Node *root = createNode (1);
  root->left = createNode (2);
  root->right = createNode (3);
  root->left->left = createNode (4);
  root->left->right = createNode (5);
  root->right->left = createNode (6);
  root->right->right = createNode (7);

  printf ("Level order traversal of binary tree: ");
  levelOrderTraversal (root);

  return 0;
}

Output:

Level order traversal of binary tree: 1 2 3 4 5 6 7

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Introduction to Trees

Binary Trees

Binary Search Trees

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

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

Introduction to Trees

Binary Trees

Binary Search Trees

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

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