## 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:

//numsis passed in by reference. (i.e., without making a copy) int len = removeDuplicates(nums); // any modification tonumsin your function would be known by the caller. // using the length returned by your function, it prints the firstlenelements. 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 =, with the first five elements of`5`

being`nums`

and`1, 1, 2, 2`

3respectively. 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 =, with the first seven elements of`7`

being modified to`nums`

,`0`

0,1,1,2,3and3respectively. It doesn't matter what values are set beyond the returned length.

**Constraints:**

`1 <= nums.length <= 3 * 10`

^{4}`-10`

^{4}<= nums[i] <= 10^{4}`nums`

is sorted in ascending order.

## Rust Solution

```
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);
}
```

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