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Merge Sort

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

Write a JavaScript program to implement the Merge Sort algorithm to sort an array of integers in ascending order. Merge Sort is a divide-and-conquer algorithm that divides the array into two halves, sorts them separately, and then merges the sorted halves back together.

Example 1
    
      
  • Input: arr = [38, 27, 43, 3, 9, 82, 10]
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  • Output: [3, 9, 10, 27, 38, 43, 82]
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  • Explanation: 
    • The initial array is [38, 27, 43, 3, 9, 82, 10]. 
    • Divide array into two halves: [38, 27, 43] and [3, 9, 82, 10]. 
    • Continue dividing until single elements: [38], [27], [43], [3], [9], [82], [10]. 
    • Merge pairs back together in sorted order: [27, 38], [43], [3, 9], [10, 82]. 
    • Continue merging until final sorted array: [3, 9, 10, 27, 38, 43, 82].
    •
Example 2
    
      
  • Input: arr = [12, 11, 13, 5, 6, 7]
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  • Output: [5, 6, 7, 11, 12, 13]
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  • Explanation: 
    • The initial array is [12, 11, 13, 5, 6, 7]. 
    • Divide into [12, 11, 13] and [5, 6, 7]. 
    • Further divide into [12], [11, 13] and [5], [6, 7]. 
    • Merge sorted pairs: [11, 12, 13] and [5, 6, 7]. 
    • Final merge produces [5, 6, 7, 11, 12, 13].
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Constraints
    
      
  • 1 ≤ arr.length ≤ 1000
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  • -1000 ≤ arr[i] ≤ 1000
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  • The array may contain duplicate elements
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  • Time Complexity: O(n log n)
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  • Space Complexity: O(n)
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Hint
Solution

Solution Hints

    
      
  • Divide the array into two halves recursively until single elements remain
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  • Create a merge function to combine two sorted arrays
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  • Use two pointers to compare elements from both halves during merging
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  • Handle remaining elements when one half is exhausted
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  • Use temporary arrays to store the divided subarrays
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  • Apply divide-and-conquer principle consistently
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Steps to solve by this approach:

 Step 1: Check base case - if array has 1 or 0 elements, it's already sorted.
 Step 2: Find the middle point to divide the array into two halves.
 Step 3: Recursively call mergeSort on the left half of the array.
 Step 4: Recursively call mergeSort on the right half of the array.
 Step 5: Create a merge function to combine two sorted arrays.
 Step 6: Use two pointers to compare elements from both halves and merge in sorted order.
 Step 7: Handle remaining elements from either array after one is exhausted.

Submitted Code :