[LeetCode] Remove Duplicate Elements from Sorted Array

Given a sorted array, 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 in place with constant memory.
For example,
Given input array A = [1,1,2],
Your function should return length = 2, and A is now [1,2].

 解题思路：
          用一个变量来统计在i位置以前总共有多少个duplicate，然后将此元素向前移动几步
Java Code:

public int removeDuplicates(int[] A) {
       int moveStep = 0;
        
        for(int i = 1; i < A.length; i++){
            if(A[i] == A[i-1]){
                moveStep++;
            }
            A[i-moveStep] = A[i];
        }
        
        return A.length - moveStep; 
    }