## 27. Remove Element

Given an array nums and a value `val`, remove all instances of that value in-place 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.

The order of elements can be changed. It doesn't matter what you leave beyond the new length.

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 as well.

Internally you can think of this:

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

// 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 = [3,2,2,3], val = 3
Output: 2, nums = [2,2]
Explanation: Your function should return length = 2, with the first two elements of nums being 2.
It doesn't matter what you leave beyond the returned length. For example if you return 2 with nums = [2,2,3,3] or nums = [2,2,0,0], your answer will be accepted.
```

Example 2:

```Input: nums = [0,1,2,2,3,0,4,2], val = 2
Output: 5, nums = [0,1,4,0,3]
Explanation: Your function should return length = `5`, with the first five elements of `nums` containing `0`, `1`, `3`, `0`, and 4. Note that the order of those five elements can be arbitrary. It doesn't matter what values are set beyond the returned length.
```

Constraints:

• `0 <= nums.length <= 100`
• `0 <= nums[i] <= 50`
• `0 <= val <= 100`

## Rust Solution

``````struct Solution;

impl Solution {
fn remove_element(nums: &mut Vec<i32>, val: i32) -> i32 {
let n: usize = nums.len();
let mut size: usize = 0;
for i in 0..n {
if nums[i] != val {
nums[size] = nums[i];
size += 1;
}
}
size as i32
}
}

#[test]
fn test() {
let mut nums = vec![3, 2, 2, 3];
let val = 3;
assert_eq!(Solution::remove_element(&mut nums, val), 2);
let mut nums = vec![0, 1, 2, 2, 3, 0, 4, 2];
let val = 2;
assert_eq!(Solution::remove_element(&mut nums, val), 5);
}
``````

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