<p>Given an array of integers <code>nums</code>, sort the array in ascending order and return it.</p>

<p>You must solve the problem <strong>without using any built-in</strong> functions in <code>O(nlog(n))</code> time complexity and with the smallest space complexity possible.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [5,2,3,1]
<strong>Output:</strong> [1,2,3,5]
<strong>Explanation:</strong> 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).
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [5,1,1,2,0,0]
<strong>Output:</strong> [0,0,1,1,2,5]
<strong>Explanation:</strong> Note that the values of nums are not necessairly unique.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 5 * 10<sup>4</sup></code></li>
	<li><code>-5 * 10<sup>4</sup> &lt;= nums[i] &lt;= 5 * 10<sup>4</sup></code></li>
</ul>


#include <vector>



class Solution {
public:
    std::vector<int> sortArray(std::vector<int>& nums) {
		sortArray(nums, 0, nums.size() - 1);

        return nums;
    }

private:
	void sortArray(std::vector<int>& nums, int left, int right) {
		if (left >= right)
			return;

		int size = right - left + 1;

		switch (size) {
			case 2:
				if (nums[left] > nums[left + 1])
					std::swap(nums[left], nums[left + 1]);
				return;
			case 3:
				if (nums[left] > nums[left + 1])
					std::swap(nums[left], nums[left + 1]);
				if (nums[left + 1] > nums[left + 2])
					std::swap(nums[left + 1], nums[left + 2]);
				if (nums[left] > nums[left + 1])
					std::swap(nums[left], nums[left + 1]);
				return;
		}

		int mid = (left + right) / 2;
		int left_left = left;
		int left_right = mid;
		int right_left = mid + 1;
		int right_right = right;

		sortArray(nums, left_left, left_right);
		sortArray(nums, right_left, right_right);

		int curr = 0;
		std::vector<int> sorted(size);

		while (left_left <= left_right && right_left <= right_right)
			sorted[curr++] = nums[left_left] < nums[right_left] ? nums[left_left++] : nums[right_left++];
		while (left_left <= left_right)
			sorted[curr++] = nums[left_left++];
		while (right_left <= right_right)
			sorted[curr++] = nums[right_left++];

		memcpy(nums.data() + left, sorted.data(), sizeof(int) * size);
	}
};
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