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# 27. Remove Element 🧹

**Difficulty**: `Easy` - **Tags**: `Array`, `Two Pointers`

## Description 📋

Given an integer array `nums` and an integer `val`, remove all occurrences of `val` in `nums` in-place. The order of the elements may be changed. Then return the number of elements in `nums` which are not equal to `val`.

Consider the number of elements in `nums` which are not equal to `val` to be `k`. To get accepted, you need to do the following things:

1. Change the array `nums` such that the first `k` elements of `nums` contain the elements which are not equal to `val`. The remaining elements of `nums` are not important, as well as the size of `nums`.
2. Return `k`.

## Custom Judge 🧪

The judge will test your solution with the following code:

```python
int[] nums = [...]; // Input array
int val = ...; // Value to remove
int[] expectedNums = [...]; // The expected answer with correct length.
                            // It is sorted with no values equaling val.

int k = removeElement(nums, val); // Calls your implementation

assert k == expectedNums.length;
sort(nums, 0, k); // Sort the first k elements of nums
for (int i = 0; i < actualLength; i++) {
    assert nums[i] == expectedNums[i];
}
```

If all assertions pass, then your solution will be accepted.

## Examples 🌟

**Example 1:**

**Input:**

```python
nums = [3,2,2,3]
val = 3
```

**Output:**

```python
2
```

**Explanation:** Your function should return `k = 2`, with the first two elements of `nums` being 2. It does not matter what you leave beyond the returned `k` (hence they are underscores).

**Example 2:**

**Input:**

```python
nums = [0,1,2,2,3,0,4,2]
val = 2
```

**Output:**

```python
5
```

**Explanation:** Your function should return `k = 5`, with the first five elements of `nums` containing 0, 0, 1, 3, and 4. Note that the five elements can be returned in any order. It does not matter what you leave beyond the returned `k` (hence they are underscores).

## Constraints ⚙️

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

## Solution 💡

### Java

```java
class Solution {
    public int removeElement(int[] nums, int val) {
        int k = 0;
        for (int i = 0; i < nums.length; i++) {
            if (nums[i] != val) {
                nums[k++] = nums[i];
            }
        }
        return k;
    }
}
```

You can find the full `Solution.java` file [here](https://github.com/ChunhThanhDe/Leetcode-Top-Interview/blob/main/Topic%201%20Array%20-%20String/002%20Remove%20Element/Solution.java).