<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 marge(vector<int>& arr,int s,int e){
     
    int mid =(s+e)/2;
    int len1 = mid - s + 1;
    int len2 = e - mid;
    int k = s;
    int *a = new int[len1];
    int *b = new int[len2];

    for(int i = 0; i < len1; i++){
        a[i] = arr[k++];
    }

    k = mid + 1;
    for(int i = 0; i < len2;i++){
        b[i] = arr[k++];
    }
    
   
    int index1 = 0;
    int index2 = 0;
     k = s;
    while(index1 < len1 && index2 < len2){
        if(a[index1] > b[index2]){
            arr[k++]  = b[index2++];
        }
        else{
            arr[k++] =a[index1++];
        }
    }
    
    while(index1 < len1){
          arr[k++] = a[index1++];
    }
    while(index2 < len2){
          arr[k++] = b[index2++];
    }

}


void margesort(vector<int>& arr,int s,int e){
    if(s >= e ){
        return;
    }

    int mid = (s+e)/2;
      margesort(arr,s,mid);
     
     margesort(arr,mid + 1,e);
      
    //merge two sorted array
    marge(arr,s,e);
  
}
    vector<int> sortArray(vector<int>& arr) {
        int n = arr.size();
        int s = 0;
        int e = n - 1;
        margesort(arr,s,e);
        return arr;
    }
};
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