CODE 50: Remove Duplicates from Sorted List II

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

.

public ListNode deleteDuplicates(ListNode head) {
// Start typing your Java solution below
// DO NOT write main() function
if (null == head) {
return null;
}
ListNode node = new ListNode(0);
ListNode next = head.next;
int currentVal = head.val;
ListNode currentNode = node;
boolean isDouble = false;
while (null != next) {
if (next.val > currentVal) {
if (!isDouble) {
currentNode.next = new ListNode(currentVal);
currentNode = currentNode.next;
}
isDouble = false;
currentVal = next.val;
} else if (next.val == currentVal) {
isDouble = true;
}
next = next.next;
}
if (!isDouble) {
currentNode.next = new ListNode(currentVal);
}
return node.next;
}