【Lintcode】112.Remove Duplicates from Sorted List

题目：

Given a sorted linked list, delete all duplicates such that each element appear only once.

Example

Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.

题解：

Solution 1 ()

class Solution {
public:
    ListNode *deleteDuplicates(ListNode *head) {
        ListNode* cur = head;
        while (cur != nullptr && cur->next != nullptr) {
            if (cur->val == cur->next->val) {
                cur->next = cur->next->next;
                continue;
            }
            cur = cur->next;
        }
        return head;
    }
};

Solution 2 ()

class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        if(!head || !head->next) return head;

        ListNode *front, *last;

        front = head;
        last = head->next;

        while(last)
        {
            if(front->val == last->val)
            {
                front->next = last->next;
                delete last;
                last = front->next;
            }
            else
            {
                front = last;
                last = last->next;
            }
        }

        return head;

    }
};