LeetCode Problem : Remove Duplicates from Sorted List II

Problem

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.

Code 

ListNode *deleteDuplicates(ListNode *head) {
    // IMPORTANT: Please reset any member data you declared, as
    // the same Solution instance will be reused for each test case.
    if(!head)
        return head;
    ListNode *prev = head;
    ListNode *curr = head;
    while(1){
        ListNode *tmp = curr;
        while(curr && tmp->val == curr->val)
            curr = curr->next;
        if(head == tmp && tmp->next != curr)
            head = curr;
        prev->next = curr;
        if(!curr)
            break;
        if(!curr->next || curr->val != curr->next->val)
            prev= curr;
    }
    return head; 
}