Remove Duplicates From Sorted Array II

solution_1.js

// Leetcode Question
// https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/?envType=study-plan-v2&envId=top-interview-150

/**
 * @param {number[]} nums
 * @return {number}
 */
var removeDuplicates = function(nums) {
    //  ASC   [1, 1, 1, 1, 1, 2, 2, 3, 4, 4, 5] 
    //  index  0  1  2  3  4  5  6  7  8  9  10
    
    let index = 0;
    const MAX_UNIQUE_ITEM_COUNT = 2;

    while (index < nums.length) {
        if(
            // do we have anything two steps ahead in the array
            nums[index + MAX_UNIQUE_ITEM_COUNT] 

            // and if current element is same as the element two steps ahead
            && (nums[index] == nums[index + MAX_UNIQUE_ITEM_COUNT])
        ) {
            pruneArray(nums, index + MAX_UNIQUE_ITEM_COUNT, nums[index]);
        }

        index += 1;
    }
};


const pruneArray = (arr, startIndex, num) => {
    let deleteCount = 0;
    let index = startIndex;
    while (index < arr.length && arr[index] == num) {
        deleteCount += 1;
        index += 1;
    }

    if (deleteCount >= 1) {
        arr.splice(startIndex, deleteCount);
    }
}