LeetCode 80. Remove Duplicates from Sorted Array II

1.题目描述

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.

2.解题思路

嗯，两个指针，扫一遍数组，O(n)

大概思路就是，前面的指针指向不出现不超过两次的，后面的指针指向出现超过两次的。

3.实现代码

class Solution {public:    int removeDuplicates(vector<int>& nums) {        if(nums.size()<=1){            return nums.size();        }        int i=0,j=1;                while(j<nums.size()){            if(nums[i]==nums[j]&&(i-1!=-1&&nums[i-1]==nums[j]))                ++j;            else{                ++i;                nums[i]=nums[j];                ++j;            }                    }        return i+1;    }};