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Merge Two Binary Trees

Certification: Basic Level Accuracy: 0% Submissions: 0 Points: 5

Write a C program to merge two binary trees. The merging rule is that if two nodes overlap, then sum the node values as the new value of the merged node. Otherwise, the non-null node will be used as the node of the new tree.

Example 1
    
  
  • Input:

    Merge Two Binary Trees Example one Input Trees
    • 
  
  • Output:


    Merge Two Binary Trees Example one Merged Tree


    
  
    • 
  
  • Explanation:
    
      
      
    • Step 1: Merge the root nodes: 1 + 2 = 3
      • 
      
    • Step 2: Merge the left child of the roots: 3 + 1 = 4
      • 
      
    • Step 3: Merge the right child of the roots: 2 + 3 = 5
      • 
      
    • Step 4: Node with value 5 in Tree 1 has no corresponding node in Tree 2, so it is carried over
      • 
      
    • Step 5: Node with value 4 in Tree 2 has no corresponding node in Tree 1, so it is carried over
      • 
      
    • Step 6: Node with value 7 in Tree 2 has no corresponding node in Tree 1, so it is carried over
      • 
    
    
  
    •
Example 2
    
  
  • Input:

    Merge Two Binary Trees Example Two Input Trees

    • 
  
  • Output:


    Merge Two Binary Trees Example Two Output Tree

    • 
  
  • Explanation:
    
      
      
    • Step 1: Merge the root nodes: 1 + 3 = 4
      • 
      
    • Step 2: Node with value 2 in Tree 1 has no corresponding node in Tree 2, so it is carried over
      • 
      
    • Step 3: Node with value 4 in Tree 2 has no corresponding node in Tree 1, so it is carried over
      • 
    
    
  
    •
Constraints
    
  
  • The number of nodes in both trees is in the range [0, 2000]
    • 
  
  • -10^4 ≤ Node.val ≤ 10^4
    • 
  
  • The merging process must start from the root nodes of both trees
    • 
  
  • Time Complexity: O(n), where n is the number of nodes in the smaller tree
    • 
  
  • Space Complexity: O(h), where h is the height of the merged tree
    •
RecursionBinary TreeTech MahindraAirbnb
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Hint
Solution

Solution Hints

    
  
  • Use a recursive approach to traverse both trees simultaneously
    • 
  
  • If both nodes exist, sum their values and create a new node with this sum
    • 
  
  • Recursively merge the left subtrees and the right subtrees
    • 
  
  • If one node is NULL, return the other node (no need to merge further in that direction)
    • 
  
  • Build the merged tree during the traversal
    • 
  
  • Handle leaf nodes and NULL pointers appropriately
    •

Steps to solve by this approach:

 Step 1: Create a base case for when either tree is NULL - return the other tree

 Step 2: Create a new node with the sum of both current node values

 Step 3: Recursively merge the left subtrees of both input trees

 Step 4: Recursively merge the right subtrees of both input trees

 Step 5: Assign the merged subtrees to the left and right children of the new merged node

 Step 6: Return the merged node, which becomes part of the parent's subtree

 Step 7: Continue this process until all nodes from both trees are processed

Submitted Code :