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Grant Riordan
Grant Riordan

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C# LeetCode 83: Remove Duplicates from Sorted List

#tutorial #csharp #programming

Problem

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.

  • Definition for singly-linked list from LeetCode. 
 public class ListNode { public int val; public ListNode next; public ListNode(int val=0, ListNode next=null) { this.val = val; this.next = next; } }
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Approach

Pretty straight-forward approach

  • Exit early to prevent unnecessary loop creation or single nodes

  • Check if the current value, is the same as the next value (i.e a duplicate), if it is then we skip over the next item by setting the next item, to the one after it with `current.next.next.

Code

`csharp
public ListNode DeleteDuplicates(ListNode head)
{
if (head == null || head.next == null)
return head;

ListNode current = head; while (current.next != null) { if (current.val == current.next.val) { // Skip the duplicate node current.next = current.next.next; } else { current = current.next; } } return head;
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}

`

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