80. Remove Duplicates from Sorted Array II

Follow up for "Remove Duplicates":
What if duplicates are allowed at most twice?

For example,
Given sorted array nums = [1,1,1,2,2,3],

Your function should return length = 5, with the first five elements of nums being 1, 1, 2, 2 and 3. It doesn't matter what you leave beyond the new length.

本题需要注意的一点是，当修改了数组的i-2个值之后，有可能当前值和第i-2是同一个值，看了答案才把这个问题解决，思路是，比较的是更改数组的第i-2个值，而不是进度-2的值，代码如下：

public class Solution {
    public int removeDuplicates(int[] nums) {
        int index=0;
        for(int i=0;i<nums.length;i++){
            if(index<2||nums[index-2]!=nums[i]){
                nums[index++] = nums[i];
            }
        }
        return index;
    }
}