<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:
    vector<int> sortArray(vector<int>& nums) {
        mergeSort(nums, 0, nums.size()-1);
        return nums;
    }
    void mergeSort(vector<int>&nums,int start,int end){
        if(start>=end)return;
        int mid = start + (end-start)/2;
        mergeSort(nums, start, mid);
        mergeSort(nums, mid+1, end);
        merge(nums, start, end, mid);
    }
    void merge(vector<int>&nums,int start,int end, int mid){
        vector<int>temp;
        int left = start, right = mid+1;

        while(left<=mid && right<=end){
            if(nums[left]<nums[right]){
                temp.push_back(nums[left]);
                left++;
            }
            else{
                temp.push_back(nums[right]);
                right++;
            }
        }
        while(left<=mid){
            temp.push_back(nums[left]);
            left++;
        }
        while(right<=end){
            temp.push_back(nums[right]);
            right++;
        }
        //pushing temp in nums.
        for(int i = start; i<=end; i++){
            nums[i] = temp[i-start];
        }
    }
};
285863