1.12 Remove Duplicates in Sorted Array

Description

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 nums = [1,1,2],

Your function should return length = 2, with the first two elements of nums being 1 and 2 respectively. It doesn't matter what you leave beyond the new length.

Method

two pointers one used to for loop each elements one used to record the difference elements entry

Time and Space Complexity

o(n)

Code

public class Solution {

  public int removeDuplicates(int[] nums) {
       if (nums == null || nums.length == 0){
           return 0;
       }
       int index = 1;
       for (int i = 1; i < nums.length; i++){
           if (nums[i] != nums[i - 1]){
               nums[index++] = nums[i];
           }
       }
       return index;
}

}