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Binary Tree Traversals

Certification: Intermediate Level Accuracy: 0% Submissions: 0 Points: 10

Write a JavaScript program to perform three different traversals of a binary tree: In-order (left, root, right), Pre-order (root, left, right), and Post-order (left, right, root). Each traversal visits all nodes in the tree but in different orders.

Example 1
    
  
  • Input: root = [1,null,2,3]
    • 
  
  • Output: 
    - Inorder: [1,3,2]  
    - Preorder: [1,2,3]
    - Postorder: [3,2,1]
    • 
  
  • Explanation: 
    • The tree has root 1, right child 2, and 2 has left child 3.
    • Inorder traversal visits left subtree, root, then right subtree.
    • Preorder traversal visits root, then left subtree, then right subtree.
    • Postorder traversal visits left subtree, right subtree, then root.
    •
Example 2
    
  
  • Input: root = [1,2,3,4,5,6,7]
    • 
  
  • Output:
    - Inorder: [4,2,5,1,6,3,7]
    - Preorder: [1,2,4,5,3,6,7]  
    - Postorder: [4,5,2,6,7,3,1]
    • 
  
  • Explanation: 
    • This is a complete binary tree with 7 nodes.
    • Each traversal follows its specific order pattern.
    • Inorder gives sorted order for BST, but this is not necessarily a BST.
    • Preorder processes root first, postorder processes root last.
    •
Constraints
    
  
  • The number of nodes in the tree is in the range [0, 100]
    • 
  
  • -100 ≤ Node.val ≤ 100
    • 
  
  • Time Complexity: O(n) for each traversal
    • 
  
  • Space Complexity: O(n) for recursion stack and result arrays
    •
RecursionBinary TreePwCD. E. Shaw
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Hint
Solution

Solution Hints

    
  
  • Use recursive approach for all three traversals
    • 
  
  • For inorder: recursively traverse left, visit root, recursively traverse right
    • 
  
  • For preorder: visit root, recursively traverse left, recursively traverse right
    • 
  
  • For postorder: recursively traverse left, recursively traverse right, visit root
    • 
  
  • Use arrays to store the traversal results and return them
    •

Steps to solve by this approach:

 Step 1: Create a result array to store the traversal order for each method.
 Step 2: Define recursive helper functions for each traversal type.
 Step 3: Handle base case - return if current node is null.
 Step 4: For inorder: recursively traverse left, add current value, recursively traverse right.
 Step 5: For preorder: add current value, recursively traverse left, recursively traverse right.
 Step 6: For postorder: recursively traverse left, recursively traverse right, add current value.
 Step 7: Call the helper function with root node and return the result array.

Submitted Code :