Remove Duplicates From Sorted List

Introduction

Hello and welcome! I’m Ming Lee, and today we’re going to cover How to solve LeetCode 83 - Remove Duplicates from Sorted List - in JS/TS ⚡

Same as always we’re gonna solve this, and we’re gonna do it without the big fancy words because this is for regular folx! Keeping it nice and casual round these parts! Movin’ on…

Problem

LeetCode 83 - Remove Duplicates from Sorted List

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.

Explanation

Now this one is going to be a bit easier than it sounds at first. Because the list is already sorted we don’t have to worry about the last sentence where it tells us to return the list sorted. So all we really need to do is check each element of the linked list and compare it to its next value. If those values are the same then the current node’s .next needs to be pushed a little further. So we’ll set current.next = current.next.next. That will cut the duplicate right out of the linked list. The code should look a little something like the following:

Solution

function deleteDuplicates(head: ListNode | null): ListNode | null {
  if(!head) return head;

  let current: ListNode = head;

  while(current.next)
    if(current.val === current.next.val)
      current.next = current.next.next;
    else
      current = current.next;

  return head;
}

Closing

Good job! I hope everyone managed to keep up on this one! Linked Lists are a really fun data structure to learn how to wrangle and they’re really cool once you learn how to use them properly. This is a great problem to come back to later if you’re feeling uncomfortable with Linked Lists, so make sure to keep it in mind when it comes to practicing! Next on the list (haha) will be LeetCode 88 - Merge Sorted Array! See you then!