# Tree Traversal : Breadth First Search (BFS)

Breadth-first search (BFS) is an algorithm for traversing or searching tree data structures. It starts at the tree root (or some arbitrary node of a graph, sometimes referred to as a search key and explores all of the neighbor nodes at the present depth prior to moving on to the nodes at the next depth level. ## Steps for Breadth First Search Tree Treaversal

• 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.

## Code for Tree Traversal : Breadth First Search

Run
```import java.util.*;
//Representing a Node of a Binary tree
class Node{
int value;
Node left,right;
//constructor
Node(int value)
{
this.value=value;
left=right=null;
}
}
{
Node root;  //Root of the Binary tree
{
root=null;
}
/*level order traversal of a binary tree */
public void levelOrder(Node ptr)
{
if(ptr==null)
return ;
//Creating a Queue Object
while(!queue.isEmpty())
{
Node node=(Node)queue.poll();  //removing an element from queue
System.out.print(node.value+" ");
if(node.left!=null)
if(node.right!=null)
}
}
}

public class Main{
public static void main(String[] args)
{
//creating the nodes of binarytree
bst.root=new Node(50);
bst.root.left=new Node(30);
bst.root.right=new Node(70);
bst.root.left.left=new Node(10);
bst.root.left.right=new Node(40);
bst.root.right.left=new Node(60);
bst.root.right.right=new Node(90);
bst.levelOrder(bst.root);
}
}```

### Output

`50 30 70 10 40 60 90 `

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### 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

### 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- CC++Java
• Spiral Order traversal of Tree- CC++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.- CC++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- CC++ | Java
• Lowest Common Ancestor in Binary Tree. CC++ | 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

### 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-
CC++Java
• Spiral Order traversal of Tree-
CC++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.-
CC++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-
CC++ | Java
• Lowest Common Ancestor in Binary Tree-
CC++ | Java