# LeetCode 80. Remove Duplicates from Sorted Array II

March 29, 2020

leetcode 80 solutions

Given a sorted array nums, remove the duplicates in-place such that duplicates appeared at most twice and return the new length.

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

Example 1

``````Given 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 respectively.

It doesn't matter what you leave beyond the returned length.``````

Example 2

``````Given nums = [0,0,1,1,1,1,2,3,3],

Your function should return length = 7, with the first seven elements of nums being modified to 0, 0, 1, 1, 2, 3 and 3 respectively.

It doesn't matter what values are set beyond the returned length.``````

## First accepted submission

``````class Solution {
public:
int removeDuplicates(vector<int>& nums) {
if (nums.size()<3) {
return nums.size();
}
int x = 0;
for(int i = 1; i<nums.size();i++) {
if (x == 0 && nums[i] == nums[x] && i==1) {
x++; //special case for i == 1;
}
if (nums[i] != nums[x]) {
nums[++x] = nums[i];
if (i<nums.size()-1 && nums[i+1] == nums[i]) {
nums[++x] = nums[i++];
}
}
}
return x+1;
}
};``````

## Second submission, cleaner code

``````class Solution {
public:
int removeDuplicates(vector<int>& nums) {
int i = 0;
for(int n : nums) {
if (i<2 || n>nums[i-2]) {
nums[i++] = n;
}
}
return i;
}
};``````