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Flatten a Nested List

Certification: Intermediate Level Accuracy: 100% Submissions: 5 Points: 10

Write a Python function to flatten a nested list of integers into a single list.

Example 1
    
  
  • Input: nested_list = [[1, 2], [3, [4, 5]], 6]
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  • Output: [1, 2, 3, 4, 5, 6]
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  • Explanation: 
      
    
    • Step 1: Start with an empty result list.
      • 
    
    • Step 2: Process [1, 2]: Add 1 and 2 to the result list. Result = [1, 2].
      • 
    
    • Step 3: Process [3, [4, 5]]: Add 3 to the result list. Result = [1, 2, 3].
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    • Step 4: Process [4, 5]: Add 4 and 5 to the result list. Result = [1, 2, 3, 4, 5].
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    • Step 5: Process 6: Add 6 to the result list. Result = [1, 2, 3, 4, 5, 6].
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    • Step 6: Return the flattened list [1, 2, 3, 4, 5, 6].
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    •
Example 2
    
  
  • Input: nested_list = [[1], [2, [3, [4]]]]
    • 
  
  • Output: [1, 2, 3, 4]
    • 
  
  • Explanation: 
      
    
    • Step 1: Start with an empty result list.
      • 
    
    • Step 2: Process [1]: Add 1 to the result list. Result = [1].
      • 
    
    • Step 3: Process [2, [3, [4]]]: Add 2 to the result list. Result = [1, 2].
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    • Step 4: Process [3, [4]]: Add 3 to the result list. Result = [1, 2, 3].
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    • Step 5: Process [4]: Add 4 to the result list. Result = [1, 2, 3, 4].
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    • Step 6: Return the flattened list [1, 2, 3, 4].
      • 
  
    •
Constraints
    
  
  • 1 <= len(nested_list) <= 1000
    • 
  
  • Time Complexity: O(n) where n is the total number of elements in the nested list
    • 
  
  • Space Complexity: O(n)
    •
ListRecursionCapgeminiDropbox
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Hint
Solution

Solution Hints

    
  
  • Use recursion to handle nested lists.
    • 
  
  • Iterate through each element, and if it is a list, recursively flatten it.
    • 
  
  • Append non-list elements directly to the result.
    •

Steps to solve by this approach:

 Step 1: Initialize an empty list to store flattened elements
 
 Step 2: Iterate through each item in the input nested list
 
 Step 3: Check if the current item is itself a list using isinstance()
 
 Step 4: If the item is a list, recursively call flatten_list on it
 
 Step 5: Add (extend) the flattened results to the output list
 
 Step 6: If the item is not a list, simply append it to the output list
 
 Step 7: Return the fully flattened list after processing all elements

Submitted Code :