[📝LeetCode #26] Remove Duplicates from Sorted Array

#leetcode #java #100daysofcode #twopointers

🎀 The Problem

Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such that each unique element appears only once. The relative order of the elements should be kept the same. Then return the number of unique elements in nums.

Example:

Input: nums = [0,0,1,1,1,2,2,3,3,4]
Output: 5, nums = [0,1,2,3,4,,,,,_]

👩‍💻 My Answer

class Solution {
    public int removeDuplicates(int[] nums) {

        int index = 0;
        int current = nums[0];
        boolean check = false;


        for (int i = 1; i < nums.length; i++) {
            int next = nums[i];

            if (check == false && current == next) {
                index++;
                check = true;
            } else if (check == true && current < next) {
                nums[index] = next;
                current = next;
                index++;
            } else if (check == false && current < next) {
                index++;
                current = next;
            }
        }

        if (check == false)
            index++;

        return index;
    }
}

Pro & Con

🔺 Runtime & Memory
✖️ Too long

💋 Ideal Answer

Approach - "Two Pointer"

I redid this problem using the "Two Pointer" approach on my own.

New Code

class Solution {
    public int removeDuplicates(int[] nums) {

        int index = 0;
        int current = 1;

        while (current < nums.length) {
            if (nums[current] != nums[index]) {
                nums[index+1] = nums[current];
                index++;
            }
            current++;
        }

        return index+1;
    }
}