solution.md

# 移除元素
以下错误的选项是？
## aop
### before
```cpp
#include <bits/stdc++.h>
using namespace std;
```
### after
```cpp
int main()
{
    Solution sol;
    int res;
    vector<int> nums{0, 1, 2, 2, 3, 0, 4, 2};
    res = sol.removeElement(nums, 2);
    cout << res;
    return 0;
}
```

## 答案
```cpp
class Solution
{
public:
    int removeElement(vector<int> &nums, int val)
    {
        int count = 0;
        for (int i = 0; i < nums.size(); i++)
        {
            if (nums[i] != val)
            {
                nums[count++] = nums[i];
            }
        }
        return count;
    }
};
```
## 选项

### A
```cpp
class Solution
{
public:
    int removeElement(vector<int> &nums, int val)
    {
        int i = 0;
        for (int j = 0; j < nums.size(); j++)
        {
            if (nums[j] != val)
            {
                nums[i] = nums[j];
                i++;
            }
        }
        return i;
    }
};
```

### B
```cpp
class Solution
{
public:
    int removeElement(vector<int> &nums, int val)
    {
        int n = nums.size();
        int i = 0;
        while (i < n)
        {
            if (nums[i] == val)
            {
                nums[i] = nums[n - 1];
                n--;
            }
            else
                i++;
        }
        return n;
    }
};
```

### C
```cpp
class Solution
{
public:
    int removeElement(vector<int> &nums, int val)
    {
        int tmp_len = nums.size();

        if (tmp_len == 0)
            return 0;
        else
        {
            for (int ii = 1; ii < nums.size(); ii++)
            {
                if (nums[ii] == val)
                    tmp_len = tmp_len - 1;
            }

            for (int i = 0; i < nums.size(); i++)
            {
                if (nums[i] == val)
                {
                    for (int j = i; j < nums.size(); j++)
                    {
                        if (nums[j] != val)
                        {
                            nums[j] = nums[i];
                        }
                    }
                }
            }

            return tmp_len;
        }
    }
};
```