26. Remove Duplicates 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 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.

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

思路：因为是排好序的数组，用index哨兵来表示前index个不重复的元素，index到i为重复的元素。