LintCode - Remove Duplicates from Sorted List

Web Link

http://www.lintcode.com/en/problem/remove-duplicates-from-sorted-list/

Description

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.

Code - C++

/**
 * Definition of ListNode
 * class ListNode {
 * public:
 *     int val;
 *     ListNode *next;
 *     ListNode(int val) {
 *         this->val = val;
 *         this->next = NULL;
 *     }
 * }
 */
class Solution {
public:
    /**
     * @param head: The first node of linked list.
     * @return: head node
     */
    ListNode *deleteDuplicates(ListNode *head) {
        // write your code here
        ListNode* current = head;
        ListNode* next_next;
        if (current == NULL) {
            return NULL;
        }
        while (current->next != NULL) {
            if (current->val == current->next->val) {
                next_next = current->next->next;
                delete current->next;
                current->next = next_next;
            } else {
                current = current->next;
            }
        }
        return head;
    }
};

Tips

Algorithm:
Traverse the list from the head (or start) node. While traversing, compare each node with its next node. If data of next node is same as current node then delete the next node. Before we delete a node, we need to store next pointer of the node