Transform array to sorted array

Question

Given an unsorted array of integers, transform the array into a sorted array in non-decreasing order. Implement a function that takes the input array and returns a new array containing the sorted elements. The solution should be efficient and handle large input sizes, adhering to optimal time and space complexity.

Codemia · Accepted Answer

The task is to transform an unsorted array of integers into a sorted array in non-decreasing order. The most suitable pattern for this problem is **Sorting**. Given that the input size can be large, we need to select an efficient sorting algorithm. QuickSort or MergeSort are common choices for efficient sorting with average time complexity of O(n log n). Here, we will use Python's built-in sorting function, which is based on Timsort, offering O(n log n) complexity in the average and worst-case scenarios.

1. **Input Validation**: Check if the input array is None or empty. If so, return an empty list.  
2. **Sorting**: Utilize Python's built-in `sorted()` function to sort the array. This function is highly optimized and handles large input sizes efficiently.  
3. **Return Result**: Return the newly sorted array.

**Example**: For an input array `[3, 1, 4, 1, 5]`, the algorithm will first check for validity. Then, it will sort the array to produce `[1, 1, 3, 4, 5]`.

```python

def transform_to_sorted_array(arr):
    # Step 1: Check for empty or None input
    if arr is None or len(arr) == 0:
        return []
    
    # Step 2: Sort the array using Python's built-in sorted function
    sorted_arr = sorted(arr)
    
    # Step 3: Return the sorted array
    return sorted_arr
```

The time complexity for the sorting operation is O(n log n) due to the efficient sorting algorithm used in Python. The space complexity is O(n) because the `sorted()` function creates a new array to hold the sorted elements. This aligns with the requirements for efficient handling of large input sizes, ensuring the solution is both time and space-efficient.

1. **Empty Array**: Input `[]` should return `[]`.  
2. **Single Element**: Input `[5]` should return `[5]`.  
3. **All Elements Identical**: Input `[2, 2, 2]` should return `[2, 2, 2]`.  
4. **Negative Numbers**: Input `[-1, -3, 0, 2]` should return `[-3, -1, 0, 2]`.  
5. **Large Numbers**: Ensure that the algorithm handles large integers, e.g., `[1000000, 999999, 1000001]` should return `[999999, 1000000, 1000001]`.

Transform array to sorted array

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