LeetCode No.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.

===================================================================

题目链接：https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/

题目大意：要求排序数组中每个数值最多出现两次，并返回新数组长度。

思路：记录每个数值个数，最多保留两个，边访问边记录。

参考代码：

class Solution {
public:
int removeDuplicates(vector<int>& nums) {
int n = nums.size() , ans = 0 ;
if ( n == 0 )
return 0 ;

for ( int i = 0 ; i < n ; i ++ )
{
int cur = nums[i] , sum = 1 ;
while ( i + 1 < n && nums[i+1] == cur )
{
i ++ ;
sum ++ ;
}
sum = sum > 2 ? 2 : sum ;
for ( int j = ans ; j < ans + sum ; j ++ )
nums[j] = cur ;
ans += sum ;
}
return ans ;
}
};