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。

 1 class Solution {

 2 public:

 3     int removeDuplicates(int A[], int n) {

 4         if(0==n) return 0;

 5         int appear =1;

 6         int index =0;

 7         for (int i=1;i<n;++i){

 8             if (A[index]==A[i]){

 9                 if (appear<2){

10                     A[++index]=A[i];

11                     ++appear;

12                 }

13             }else{

14                 A[++index]=A[i];

15                 appear =1;

16             }

17         }

18         return index+1;

19         

20     }

21 };