LeetCode OJ：Remove Duplicates from Sorted Array II（移除数组中的重复元素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.

典型的双指针问题，维护两个指针不断更新就可以了，代码如下：

class Solution {
public:
int removeDuplicates(vector<int>& nums) {
int sz = nums.size();
if(!sz) return 0;
int start = 0;//第二个指针
int i = 0;//第一个指针
int count = 0;
int key = nums[0];
for(; i < sz; ++i){
if(nums[i] == key)
count++;
else{
for(int k = 0; k < min(2, count); ++k)
nums[start++] = key;//更改数组元素，指针前移
key = nums[i];
count = 1;
}
}
for(int k = 0; k < min(2, count); ++k)
nums[start++] = key;
return start;
}
};