Leetcode: Remove Duplicates from Sorted Array II(80)

Problem no. 80 (Remove Duplicates from Sorted Array II) using JavaScript.

Day 4:

Photo by Pankaj Patel on Unsplash

So, the problem I chose to start for the fourth day is the Array problem in the Leetcode Top Interview 150 series.

I will solve all the problems only in JavaScript, I know most people use C++, Java, or Python to solve DSA problems, but why not try something different?

Let’s start:
The problem states that:

Example 1:

Input:
nums = [0,0,1,1,1,1,2,3,3]

Output:
k = 7, nums = [0,0,1,1,2,3,3,_,_]

Explanation: Your function should return k = 7, with the first seven elements of nums being 0, 0, 1, 1, 2, 3, and 3 respectively.
It does not matter what you leave beyond the returned k (hence they are underscores).

Code:

Solution 1:

const arrayLength = nums.length;
    let trackCountElement = countOccurence(nums);

    let p1 = 0;
    for (let i = 0; i < arrayLength; i++) {
        if (trackCountElement[nums[p1]] > 2) {
            nums.splice(p1, 1);
            trackCountElement = countOccurence(nums);
        } else {
            p1++;
        }
    }

function countOccurence(arr) {
    const trackCountElement = {};
    for (let i = 0; i < arr.length; i++) {
        if (!trackCountElement[arr[i]]) {
            trackCountElement[arr[i]] = 1
        } else {
            trackCountElement[arr[i]]++
        }
    }
    return trackCountElement;
}

Solution 2:

 let c = 0;

    for (let i = 0; i < nums.length; i++) {
        if (nums[i] !== nums[i + 2]) {
            nums[c] = nums[i];
            c++
        }
    }

    return c;

So, I’ll explain solution 1 as solution 2 is self-explanatory:-

• We create a function named countOccurence, which will return the occurrence of each element in the array.
• Then we’ll loop through our array and check which element has an occurrence in the array more than 2.
• If there is an element that has an occurrence of more than 2 then we delete that element using the splice function and again track the occurrence of each element in the new array.
• If not greater than 2, then we increase the variable p1.

It’s a long way to solve it, but that is my first solution and when I solved this problem again I solved it using Solution 2.

It’s a self-explanatory solution for all of you as I only used basic JavaScript functions. If anyone has doubts, please let me know in the comment section.

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