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Binary Tree Level Order Traversal

Certification: Intermediate Level Accuracy: 0% Submissions: 0 Points: 15

Write a C program to perform level order traversal of a binary tree. Level order traversal visits all nodes at the current depth before moving to nodes at the next depth level. Return the result as a 2D array where each sub-array contains the values of nodes at each level.

Example 1
    
  
  • Input: Tree structure [3,9,20,null,null,15,7]
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  • Output: [[3],[9,20],[15,7]]
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  • Explanation: 
    • Level 0 contains only the root node 3. 
    • Level 1 contains nodes 9 and 20. 
    • Level 2 contains nodes 15 and 7. 
    • Therefore, level order traversal is [[3],[9,20],[15,7]].
    •
Example 2
    
  
  • Input: Tree structure [1]
    • 
  
  • Output: [[1]]
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  • Explanation: 
    • The tree has only one node at level 0. 
    • Level 0 contains only the root node 1. 
    • Therefore, level order traversal is [[1]].
    •
Constraints
    
  
  • The number of nodes in the tree is in the range [0, 2000]
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  • -1000 ≤ Node.val ≤ 1000
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  • You must traverse level by level from left to right
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  • Time Complexity: O(n)
    • 
  
  • Space Complexity: O(w) where w is the maximum width of the tree
    •
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Hint
Solution

Solution Hints

    
  
  • Use a queue data structure to implement level order traversal
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  • Start by adding the root node to the queue
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  • For each level, process all nodes currently in the queue
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  • Add the children of processed nodes to the queue for the next level
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  • Keep track of the number of nodes at each level
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  • Store the values of nodes at each level in separate arrays
    •

Steps to solve by this approach:

 Step 1: Initialize a queue and add the root node to it.
 Step 2: Create result array to store level-wise traversal.
 Step 3: While queue is not empty, get the current level size.
 Step 4: Process all nodes at the current level by dequeuing them.
 Step 5: Store the values of current level nodes in the result array.
 Step 6: Add the children of processed nodes to the queue for next level.
 Step 7: Increment the level count and repeat until queue is empty.

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