<p>Given the <code>head</code> of a linked list, return <em>the list after sorting it in <strong>ascending order</strong></em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/09/14/sort_list_1.jpg" style="width: 450px; height: 194px;" />
<pre>
<strong>Input:</strong> head = [4,2,1,3]
<strong>Output:</strong> [1,2,3,4]
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/09/14/sort_list_2.jpg" style="width: 550px; height: 184px;" />
<pre>
<strong>Input:</strong> head = [-1,5,3,4,0]
<strong>Output:</strong> [-1,0,3,4,5]
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> head = []
<strong>Output:</strong> []
</pre>

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

<ul>
	<li>The number of nodes in the list is in the range <code>[0, 5 * 10<sup>4</sup>]</code>.</li>
	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
</ul>

<p>&nbsp;</p>
<p><strong>Follow up:</strong> Can you sort the linked list in <code>O(n logn)</code> time and <code>O(1)</code> memory (i.e. constant space)?</p>

/**
 * Definition for singly-linked list.
  * struct ListNode {
   *     int val;
    *     ListNode *next;
     *     ListNode() : val(0), next(nullptr) {}
      *     ListNode(int x) : val(x), next(nullptr) {}
       *     ListNode(int x, ListNode *next) : val(x), next(next) {}
        * };
         */
         class Solution {
         public:
             ListNode* sortList(ListNode* head) {
                     ListNode* curr=head;
                             vector<int> val;
                                     while(curr){
                                                 val.push_back(curr->val);
                                                                     ListNode* temp=curr;
                                                                                 curr=curr->next;
                                                                                             delete temp;
                                                                                                     }
                                                                                                             sort(val.begin(),val.end());

                                                                                                                     ListNode* heads=NULL;
                                                                                                                             ListNode* prev=NULL;
                                                                                                                                     for(auto i : val){

                                                                                                                                                 ListNode* temp=new ListNode(i);
                                                                                                                                                             if(heads==NULL){
                                                                                                                                                                             heads=temp;
                                                                                                                                                                                             prev=temp;
                                                                                                                                                                                                         }else{
                                                                                                                                                                                                                         prev->next=temp;
                                                                                                                                                                                                                                         prev=temp;
                                                                                                                                                                                                                                                     }

                                                                                                                                                                                                                                                             }
                                                                                                                                                                                                                                                                          



                                                                                                                                                                                                                                                                                  return heads;


                                                                                                                                                                                                                                                                                      }
                                                                                                                                                                                                                                                                                      };
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