80. Remove Duplicates from Sorted Array II

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.

Clarification:

Confused why the returned value is an integer, but your answer is an array?

Note that the input array is passed in by reference, which means a modification to the input array will be known to the caller.

Internally you can think of this:

```// nums is passed in by reference. (i.e., without making a copy)
int len = removeDuplicates(nums);

// any modification to nums in your function would be known by the caller.
// using the length returned by your function, it prints the first len elements.
for (int i = 0; i < len; i++) {
print(nums[i]);
}
```

Example 1:

```Input: nums = [1,1,1,2,2,3]
Output: 5, nums = [1,1,2,2,3]
Explanation: 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:

```Input: nums = [0,0,1,1,1,1,2,3,3]
Output: 7, nums = [0,0,1,1,2,3,3]
Explanation: 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.
```

Constraints:

• `1 <= nums.length <= 3 * 104`
• `-104 <= nums[i] <= 104`
• `nums` is sorted in ascending order.

80. Remove Duplicates from Sorted Array II
``````struct Solution;

impl Solution {
fn remove_duplicates(nums: &mut Vec<i32>) -> i32 {
let n = nums.len();
let mut m = 0;
let mut prev: Option<(i32, usize)> = None;
for i in 0..n {
if let Some((value, count)) = prev {
if value == nums[i] {
if count == 1 {
prev = Some((nums[i], 2));
nums[m] = nums[i];
m += 1;
}
} else {
prev = Some((nums[i], 1));
nums[m] = nums[i];
m += 1;
}
} else {
prev = Some((nums[i], 1));
nums[m] = nums[i];
m += 1;
}
}
m as i32
}
}

#[test]
fn test() {
let mut nums = vec![1, 1, 1, 2, 2, 3];
let res = 5;
assert_eq!(Solution::remove_duplicates(&mut nums), res);
}
``````