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.
给定一个有序数组，删除重复内容，使每个元素只出现一次并返回新的长度。
不要为其他数组分配额外空间，您必须通过在O（1）额外内存中就地修改输入数组来实现此目的。
例：
给定nums = [1,1,2]，
你的函数应该返回length = 2，num的前两个元素分别是1和2。
无论你在新的长度以外留下什么都没有关系。