// https://leetcode.com/problems/remove-duplicates-from-sorted-list/ 

#include <iostream>

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* deleteDuplicates(ListNode* head) {
        if (head == nullptr)
            return head;
        bool newSequence = false;
        int currentVal = head->val;
        ListNode* front = head->next;
        ListNode* rear = head;
        while (front != nullptr) {
            if (front->val != currentVal) {
                std::cout << "Previous value: " << currentVal << "; current value: " << front->val << '\n';
                rear->next = front;
                currentVal = front->val;
                rear = front;
            }
            front = front->next;
        }
        rear->next = nullptr;
        return head;
    }
};