Remove Duplicates from Sorted Array

Question: Given a sorted array nums, remove the duplicates in-place such that each element appear only once and return the new length.

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

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Approach:

Today, let’s just dive straight into the code.

//Approach
//Runtime: 5ms
//Memory usage: 40.4MB
class Solution {
    public int removeDuplicates(int[] nums) {
        if(nums.length==0){
            return 0;
        }
        int currVacant = 1;
        for(int i = 1; i<nums.length; i++){
            if(nums[currVacant-1]!=nums[i]){
                //Don't have to move the element, 
                //if it's already in the right position
                if(currVacant!=i){
                    nums[currVacant] = nums[i];
                }
                currVacant++;
            }
            //Can skip redundantly checking 
            //the last set of duplicates all together
            if(nums[i]==nums[nums.length-1]){
                break;
            }
        }
        return currVacant;
    }
}

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Cheers & Chao!