0080-remove-duplicates-from-sorted-array-ii.js

/**
 * https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/
 *
 * Time O(n) | Space O(1)
 * @param {number[]} nums
 * @return {number}
 */
var removeDuplicates = function (nums) {
    let current = nums[0];
    let sameElCount = 0;

    for (let i = 0; i < nums.length; i++) {
        if (current === nums[i]) {
            sameElCount++;
        }
        if (current !== nums[i]) {
            current = nums[i];
            sameElCount = 1;
        }
        if (sameElCount > 2) {
            nums.splice(i, 1);
            i--;
        }
    }
};

/**
 * Two pointer
 * Time O(n^2) | Space O(1)
 * @param {number[]} nums
 * @return {number}
 */
var removeDuplicates2 = function (nums) {
    const isEdgeCase = nums.length < 2;
    if (isEdgeCase) return nums.length;

    let [left, right] = [2, 2];

    while (right < nums.length) {
        /* Time O(N) */
        const isEqual = nums[left - 2] === nums[right];
        if (!isEqual) {
            nums[left] = nums[right];
            left += 1;
        }

        right += 1;
    }
    return left;
};