算法 Java Leetcode

Delete all duplicates in a sorted linked list.

Question

Given a sorted linked list, delete all duplicates such that each element appear only once.
See it on Leetcode

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For example,
Given "1->1->2", return "1->2".
Given "1->1->2->3->3", return "1->2->3".

Hint

This is a simple problem that merely tests your ability to manipulate list node pointers. Because the input list is sorted, we can determine if a node is a duplicate by comparing its value to the node after it in the list. If it is a duplicate, we change the next pointer of the current node so that it skips the next node and points directly to the one after the next node.

Solution

  • java
  • cpp
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/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        ListNode current = head;
        while (current != null && current.next != null) {
            if (current.next.val == current.val) {
                current.next = current.next.next;
            } else {
                current = current.next;
            }
        }
        return head;
    }
}