<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>

class Solution {
public:
    void merge(vector<int>& nums, int st, int mid, int end) {
        int i = st;
        int j = mid +1;
        vector<int> res;
        while (i <= mid && j <= end) {
            if (nums[i] <= nums[j]) {
                res.push_back(nums[i]);
                i++;
            } else {
                res.push_back(nums[j]);
                j++;
            }
        }
        while(i<=mid){
            res.push_back(nums[i]);
            i++;
        }
        while(j<=mid){
            res.push_back(nums[j]);
            j++;
        }
        for(int i=0;i<res.size();i++){
            nums[st+i]=res[i];
        }
    }
    void util(vector<int>& nums, int st, int end) {
        if (st == end)
            return;

        int mid = (st + end) / 2;
        util(nums, st, mid);
        util(nums, mid + 1, end);
        merge(nums, st, mid, end);
    }
    vector<int> sortArray(vector<int>& nums) {
        int n = nums.size();
        int st = 0;
        int end = n - 1;
        util(nums, 0, end);
        return nums;
    }
};
244193