Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.
Example 1:
Input: 1->2->3->3->4->4->5
Output: 1->2->5
Example 2:
Input: 1->1->1->2->3
Output: 2->3
递归和迭代:
public ListNode deleteDuplicates(ListNode head) {
if(head == null || head.next == null) return head;
int val = head.val;
ListNode p = head.next;
if(head.val != p.val){
head.next = deleteDuplicates(p);
return head;
}
else{
while(p != null && val == p.val) p = p.next;
return deleteDuplicates(p);
}
}
public ListNode deleteDuplicates(ListNode head) {
if(head == null || head.next == null) return head;
ListNode dummy = new ListNode(0);
dummy.next = head;
ListNode pre = dummy;
ListNode cur = head;
while(cur != null){
while(cur.next != null && cur.next.val == cur.val){
cur = cur.next;
}
if(pre.next == cur){
pre = pre.next;
cur = cur.next;
}else{
pre.next = cur.next;
cur = cur.next;
}
}
return dummy.next;
}