#include <iostream>

struct ListNode 
{
    int val;
    ListNode *next;
    ListNode(int x = 0) : val(x), next(NULL) {}
};


ListNode * RemoveDuplicated(ListNode *head)
{
    if (head == NULL) return head;

    ListNode** last = &head;
    ListNode* p = head;
    if (p->next == NULL || p->val != p->next->val)
    {
        *last = p;
        last = &(p->next);
    }
    int val = p->val;
	
    while((p = p->next) != NULL)
        if (p->val != val)
        {
            if (p->next == NULL || p->val != p->next->val)
            {
                *last = p;
                last = &(p->next);
            }
            val = p->val;
        }

    *last = NULL;

    return head;
}
  
using namespace std;

void PrintList(ListNode* h)
{
    while(h)
    {
        cout << h->val << ',';
        h = h->next;
    }

    cout << endl;
}

int main(int argc, char** argv)
{
    int A[] = {1,2,2,2,2,3,4,4,5,6,6,7,8,8,8,9,10,10};
    int n =sizeof(A)/sizeof(int);
    ListNode L[n];

    for (int i = 0; i < n-1; ++i)
    {
        L[i].val = A[i];
        L[i].next = L+(i+1);
    }
    L[n-1].val = A[n-1];
    
    PrintList(L);
    PrintList(RemoveDuplicated(L));
    return 0;
}