LeetCode-in-Java

83. Remove Duplicates from Sorted List

Easy

Given the head of a sorted linked list, delete all duplicates such that each element appears only once. Return the linked list sorted as well.

Example 1:

Input: head = [1,1,2]

Output: [1,2]

Example 2:

Input: head = [1,1,2,3,3]

Output: [1,2,3]

Constraints:

• The number of nodes in the list is in the range [0, 300].
• -100 <= Node.val <= 100
• The list is guaranteed to be sorted in ascending order.

Solution

import com_github_leetcode.ListNode;

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

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