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Merge Two Sorted Arrays

Certification: Basic Level Accuracy: 25% Submissions: 4 Points: 5

Write a JavaScript program to merge two sorted arrays into a single sorted array. The merged array should contain all elements from both input arrays in ascending order. You cannot use built-in sort functions.

Example 1
    
  
  • Input: nums1 = [1,2,3,0,0,0], m = 3, nums2 = [2,5,6], n = 3
    • 
  
  • Output: [1,2,2,3,5,6]
    • 
  
  • Explanation: 
    • nums1 has 3 valid elements [1,2,3] and nums2 has 3 elements [2,5,6]. 
    • Merge process starts from the end of both arrays. 
    • Compare elements and place the larger one at the end of nums1. 
    • Continue until all elements from nums2 are merged into nums1.
    •
Example 2
    
  
  • Input: nums1 = [1], m = 1, nums2 = [], n = 0
    • 
  
  • Output: [1]
    • 
  
  • Explanation: 
    • nums1 has 1 element [1] and nums2 is empty. 
    • Since nums2 is empty, the result is just nums1. 
    • No merging is required.
    •
Constraints
    
  
  • nums1.length == m + n
    • 
  
  • nums2.length == n
    • 
  
  • 0 ≤ m, n ≤ 200
    • 
  
  • 1 ≤ m + n ≤ 200
    • 
  
  • -10^9 ≤ nums1[i], nums2[j] ≤ 10^9
    • 
  
  • You must merge in-place with O(1) extra memory space
    •
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Hint
Solution

Solution Hints

    
  
  • Use three pointers: one for nums1 valid elements, one for nums2, and one for the final position
    • 
  
  • Start merging from the end of both arrays to avoid overwriting elements
    • 
  
  • Compare elements from the end of both arrays and place the larger one at the end
    • 
  
  • Continue until all elements from nums2 are processed
    • 
  
  • Handle remaining elements in nums2 if any
    • 
  
  • The merge should be done in-place in nums1 array
    •

Steps to solve by this approach:

 Step 1: Initialize three pointers - i for valid elements in nums1, j for nums2, and k for final position.
 Step 2: Set i to m-1, j to n-1, and k to m+n-1 to start from the end of arrays.
 Step 3: Compare elements at nums1[i] and nums2[j] and place the larger one at nums1[k].
 Step 4: Move the corresponding pointer (i or j) and k backward after each placement.
 Step 5: Continue the comparison and placement until one of the arrays is exhausted.
 Step 6: Copy any remaining elements from nums2 to nums1 if j >= 0.
 Step 7: The merge is complete as nums1 now contains all elements in sorted order.

Submitted Code :