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Flatten Deeply Nested Array

Certification: Intermediate Level Accuracy: 100% Submissions: 1 Points: 10

Write a JavaScript function to flatten a deeply nested array without using any built-in methods like Array.flat() or Array.concat(). The function should take a nested array of any depth and return a single-dimensional array containing all elements in their original order.

Example 1
    
      
  • Input: arr = [1, [2, 3], [4, [5, 6]], 7]
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  • Output: [1, 2, 3, 4, 5, 6, 7]
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  • Explanation: 
    • The input array contains nested arrays at different levels. 
    • We traverse through each element and check if it's an array. 
    • If an element is an array, we recursively flatten it. 
    • All elements are collected in a single flat array. 
    • The result maintains the original order of elements.
    •
Example 2
    
      
  • Input: arr = [[[1, 2]], [3, [4, [5]]]]
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  • Output: [1, 2, 3, 4, 5]
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  • Explanation: 
    • The input has multiple levels of nesting. 
    • We recursively process each nested array. 
    • Elements 1 and 2 are extracted from the triple-nested array. 
    • Elements 3, 4, and 5 are extracted from their respective nested positions. 
    • All elements are combined into a single flat array.
    •
Constraints
    
      
  • The array can contain any type of elements (numbers, strings, objects, etc.)
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  • The nesting depth can be arbitrary
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  • You cannot use built-in flattening methods like Array.flat(), Array.concat()
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  • Time Complexity: O(n) where n is the total number of elements
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  • Space Complexity: O(d) where d is the maximum depth of nesting
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ArraysRecursionIBMHCL Technologies
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Solution

Solution Hints

    
      
  • Use recursion to handle nested arrays at any depth
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  • Check if each element is an array using Array.isArray()
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  • If the element is an array, recursively call the flatten function
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  • If the element is not an array, add it directly to the result
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  • Use the spread operator or push method to combine results
    •

Steps to solve by this approach:

 Step 1: Initialize an empty result array to store flattened elements.
 Step 2: Iterate through each element in the input array.
 Step 3: Check if the current element is an array using Array.isArray().
 Step 4: If it's an array, recursively call the flatten function and concatenate results.
 Step 5: If it's not an array, push the element directly to the result array.
 Step 6: Continue until all elements are processed.
 Step 7: Return the flattened result array.

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