Remove Duplicates from Sorted Array

题目:
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 by **modifying the input array in-place with O(1) extra memory.

Example:

Given 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.

分析:
maintain 2个index i 和 j, j > i
i和i的左边的所有元素都是没有duplicates的
从j = i+1开始往右扫描，如果nums[j]不等于nums[i], 那么就找到了一个非duplicate的元素，把这个元素放置在nums[i+1],并且让i自增1.如果nums[j]等于nums[i], 则使j自增1，跳过这个duplicate的元素

    public int removeDuplicates(int[] nums) {
        if(nums.length <= 1) return nums.length;
        int n = nums.length, size = 1, j = 1;
        while(j < n) {
            if(nums[j] != nums[size - 1]) {
                nums[size++] = nums[j];
            }
            j++;
        }
        return size;
    }