Remove Duplicates from Sorted Array II

http://oj.leetcode.com/problems/remove-duplicates-from-sorted-array-ii/

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

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

Your function should return length = 5, and A is now [1,1,2,2,3].

Solution:

由于数组已经排序，所以只需要增加一个变量来记录元素出现的次数；若没有排序，需要使用hash来记录每个元素的出现次数。

class Solution {
public:
    int removeDuplicates(int A[], int n) {
        if(0==n) return 0;
        int appear =1;
        int index =0;
        for (int i=1;i<n;++i){
            if (A[index]==A[i]){
                if (appear<2){
                    A[++index]=A[i];
                    ++appear;
                }
            }else{
                A[++index]=A[i];
                appear =1;
            }
        }
        return index+1;
        
    }
};