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.

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題目鏈接：https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/

題目大意：要求排序數組中每個數值最多出現兩次，並返回新數組長度。

思路：記錄每個數值個數，最多保留兩個，邊訪問邊記錄。

參考代碼：

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 ;
    }
};