Merge Two Unsorted Arrays into the First Array

Question

The question asks you to merge two unsorted integer arrays, where the first array has enough space to accommodate all elements of the second array, and then sort the merged array in ascending order.

Codemia · Accepted Answer

To solve the problem, we need to merge the two arrays into the first array and then sort the resulting array. The approach involves two main steps: merging the elements of the second array into the first array and then applying a sorting algorithm to arrange the elements in ascending order.

1. **Merge the Arrays**: We will iterate through the second array and copy its elements into the first array starting from the index where the placeholders begin.
2. **Sort the Merged Array**: After merging, we will sort the entire first array using a sorting algorithm such as QuickSort or Python's built-in sort function.

Here's a sample implementation in Python:
```python
def merge_and_sort(a, b):
    # Step 1: Merge b into a
    n = len(a)
    m = len(b)
    for i in range(m):
        a[n - m + i] = b[i]
    # Step 2: Sort the merged array
    a.sort()
    return a

# Example usage:
a = [5, 1, 3, 0, 0, 0]
b = [6, 2, 4]
result = merge_and_sort(a, b)
print(result)  # Output: [1, 2, 3, 4, 5, 6]
```

The time complexity of the merging step is O(m), where m is the length of array b. The sorting step has a time complexity of O(n log n), where n is the total number of elements in array a after merging. Therefore, the overall time complexity is O(n log n). The space complexity is O(1) since we are modifying the first array in place.

Consider the following edge cases:
- If array b is empty, the output should simply be the sorted version of array a.
- If array a is already sorted, the final output should still be sorted and include elements from b.
- If both arrays are empty, the output should also be an empty array.

Interviewers are looking for clarity in your thought process, the ability to articulate your approach, and a solid understanding of algorithm efficiency. They may also assess how well you handle edge cases and whether you can optimize your solution if necessary.

Merge Two Unsorted Arrays into the First Array

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