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
Solution
- Iterative
- Recursive
Code
public class Solution {
public ListNode deleteDuplicates_1(ListNode head) {
ListNode dummy = new ListNode(-1);
ListNode cur = dummy;
while (head != null) {
if (head.next != null && head.val == head.next.val) {
while (head.next != null && head.val == head.next.val)
head = head.next;
} else {
cur.next = head;
cur = cur.next;
}
head = head.next;
}
cur.next = null;
return dummy.next;
}
public ListNode deleteDuplicates(ListNode head) {
if (head == null) return null;
if (head.next == null || head.val != head.next.val){
head.next = deleteDuplicates(head.next);
return head;
}
while (head.next != null && head.val == head.next.val)
head = head.next;
return deleteDuplicates(head.next);
}
}