> ## Documentation Index
> Fetch the complete documentation index at: https://leetcode-py.wisl.dev/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> leetcode-py is a Python LeetCode practice environment generator with one CLI: lcpy. It is not a service or platform.
> Each problem is a directory under leetcode/ with README.md, solution.py, test_solution.py, helpers.py, and playground.ipynb. lcpy gen creates them from JSON templates bundled with the package.
> Examples are backed by tests; copy them verbatim.

# Sort an Array Python Solution with Tests

> Tested Python solution for LeetCode 912 with 18 pytest cases. Generate a practice environment with lcpy.

LeetCode 912, Medium. Topics: Array, Divide and Conquer, Sorting, Heap (Priority Queue), Merge Sort, Bucket Sort, Radix Sort, Counting Sort. [View on LeetCode](https://leetcode.com/problems/sort-an-array/description/).

Generate this problem as a practice environment: tested reference solution, 18 [parametrized pytest cases](/practice/testing), and a playground notebook:

```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
lcpy gen -n 912   # by problem number
lcpy gen -s sort_an_array   # by problem name
```

## Problem

Given an array of integers `nums`, sort the array in ascending order and return it.

You must solve the problem **without using any built-in** functions in `O(nlog(n))` time complexity and with the smallest space complexity possible.

### Examples

```
Input: nums = [5,2,3,1]
Output: [1,2,3,5]
Explanation: After sorting the array, the positions of some numbers are not changed (for example, 2 and 3), while the positions of other numbers are changed (for example, 1 and 5).
```

```
Input: nums = [5,1,1,2,0,0]
Output: [0,0,1,1,2,5]
Explanation: Note that the values of nums are not necessarily unique.
```

### Constraints

* 1 \<= nums.length \<= 5 \* 10^4
* -5 \* 10^4 \<= nums\[i] \<= 5 \* 10^4

## Solution

Reference implementation from [solution.py on GitHub](https://github.com/wislertt/leetcode-py/blob/main/leetcode/sort_an_array/solution.py), full suite in [test\_solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/sort_an_array/test_solution.py):

```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
class Solution:
    # Time: O(n log n)
    # Space: O(n)
    def sort_array(self, nums: list[int]) -> list[int]:
        if len(nums) <= 1:
            return nums

        mid = len(nums) // 2
        left = self.sort_array(nums[:mid])
        right = self.sort_array(nums[mid:])

        merged: list[int] = []
        i = j = 0
        while i < len(left) and j < len(right):
            if left[i] <= right[j]:
                merged.append(left[i])
                i += 1
            else:
                merged.append(right[j])
                j += 1
        merged.extend(left[i:])
        merged.extend(right[j:])
        return merged
```

## Complexity

| Time       | Space |
| ---------- | ----- |
| O(n log n) | O(n)  |

## Tags

[NeetCode 250](/catalog/neetcode-250), [NeetCode All](/catalog/neetcode).