82 Remove Duplicates from Sorted List II
1. Question
Given a sorted linked list, delete all nodes that have duplicate numbers, leaving onlydistinctnumbers from the original list.
For example,
Given1->2->3->3->4->4->5
, return1->2->5
.
Given1->1->1->2->3
, return2->3
.
2. Implementation
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode deleteDuplicates(ListNode head) {
ListNode dummy = new ListNode(0);
dummy.next = head;
ListNode preNode = dummy, curNode = head;
while (curNode != null) {
while (curNode.next != null && curNode.val == curNode.next.val) {
curNode = curNode.next;
}
if (preNode.next != curNode) {
preNode.next = curNode.next;
}
else {
preNode = preNode.next;
}
curNode = curNode.next;
}
return dummy.next;
}
}
3. Time & Space Complexity
时间复杂度O(n), 空间复杂度O(1)
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