<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 start,int mid,int end){

        vector<int>arr(end-start+1);

        int i=start;
        int j=mid+1;

       int z=0;
       while (i<=mid && j<=end){
            if(nums[i]<nums[j]){
            arr[z]=nums[i];
            z=z+1;
            i=i+1;    
            }
            else {                
                arr[z]=nums[j];
                 z=z+1;
                j=j+1;      
            }     
        }  

        while(i<=mid){
            arr[z]=nums[i];
            z=z+1;
            i=i+1;       
            }     

            while(j<=end){
            arr[z]=nums[j];
             z=z+1;
             j=j+1;  
            }

            int p=0;
        for(int k=start;k<=end;k++){
            // if(p<(end-start+1)){
            nums[k]=arr[p];
            p++;
            // }
        }

    }
      
    void helper(vector<int> &nums,int start,int end){
        if(start>=end) 
        return ;

        int mid=(end-start)/2+start;

        helper(nums,start,mid);
        helper(nums,mid+1,end);

        merge(nums,start,mid,end);

    }
    
    vector<int> sortArray(vector<int>& nums) {
        int start=0;
        int end=nums.size()-1;

        helper(nums,start,end);  

        return nums; 
    }
};
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