148. Sort List

Problem Description
https://leetcode.com/problems/sort-list/description/

/**
 * 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) {
        if (head == NULL) {
            return head;
        }

        ListNode* temp = head;
       
        vector<int> v;
        while (temp != NULL) {
            v.push_back(temp->val);
            temp = temp->next;
        }

        delete(temp);
        sort(v.begin(), v.end());
        ListNode* dummy = new ListNode(v[0]);

        head = dummy;
        for (auto i : v) {
            ListNode* t = new ListNode(i);
            dummy->next = t;
            dummy = dummy->next;
        }
        return head->next;
    }
};