he-026

# HumanEval/26

Implement a file **`solution.py`** that completes the function below. Keep the given name and signature; your file must define it at module level.

```python
from typing import List


def remove_duplicates(numbers: List[int]) -> List[int]:
    """ From a list of integers, remove all elements that occur more than once.
    Keep order of elements left the same as in the input.
    >>> remove_duplicates([1, 2, 3, 2, 4])
    [1, 3, 4]
    """
```

<!-- imported from OpenAI HumanEval (HumanEval/26) -->

# Auto-generated from OpenAI HumanEval HumanEval/26. Do not edit by hand.
from solution import *  # noqa: F401,F403 (prompt helpers may be referenced by tests)
from solution import remove_duplicates as candidate

METADATA = {
    'author': 'jt',
    'dataset': 'test'
}


def check(candidate):
    assert candidate([]) == []
    assert candidate([1, 2, 3, 4]) == [1, 2, 3, 4]
    assert candidate([1, 2, 3, 2, 4, 3, 5]) == [1, 4, 5]


def test_he_026():
    check(candidate)

You are an expert programmer. Solve the task exactly as specified. Output your solution as fenced code blocks using the required file name(s) and the exact function/type signatures requested. Prefer correctness; do not include prose outside code unless asked.

```python
from typing import List
from collections import Counter

def remove_duplicates(numbers: List[int]) -> List[int]:
    counts = Counter(numbers)
    return [num for num in numbers if counts[num] == 1]
```

The user wants a Python function `remove_duplicates` that takes a list of integers and returns a new list containing only the elements that appear exactly once in the original list, preserving their original order.

Let's analyze the example:
Input: `[1, 2, 3, 2, 4]`
Counts:
1: 1
2: 2
3: 1
4: 1
Elements with count == 1: 1, 3, 4
Output: `[1, 3, 4]`

Algorithm:
1. Count the occurrences of each number in the input list.
2. Iterate through the input list and keep only those numbers whose count is exactly 1.
3. Return the resulting list.

Implementation details:
We can use `collections.Counter` to count occurrences efficiently.
Then list comprehension to filter.

```python
from typing import List
from collections import Counter

def remove_duplicates(numbers: List[int]) -> List[int]:
    counts = Counter(numbers)
    return [num for num in numbers if counts[num] == 1]
```

Let's double check constraints and edge cases.
- Empty list: `[]` -> `[]` (works)
- All duplicates: `[1, 1, 2, 2]` -> `[]` (works)
- All unique: `[1, 2, 3]` -> `[1, 2, 3]` (works)
- Negative numbers: `[-1, -1, 2]` -> `[2]` (works)
- Order preservation: The list comprehension iterates over `numbers` in order, so order is preserved.

The problem statement says "remove all elements that occur more than once." This implies keeping elements that occur exactly once.
The docstring example confirms this: `[1, 2, 3, 2, 4]` -> `[1, 3, 4]`.

One minor point: `from typing import List` is already in the prompt. I should include it or assume it's there. The prompt says "Keep the given name and signature; your file must define it at module level."

I will write the complete `solution.py`.

```python
from typing import List
from collections import Counter

def remove_duplicates(numbers: List[int]) -> List[int]:
    counts = Counter(numbers)
    return [num for num in numbers if counts[num] == 1]
```

Wait, should I import `Counter` inside the function or at the top? Top is fine.
The prompt gives:
```python
from typing import List


def remove_duplicates(numbers: List[int]) -> List[int]:
    """ From a list of integers, remove all elements that occur more than once.
    Keep order of elements left the same as in the input.
    >>> remove_duplicates([1, 2, 3, 2, 4])
    [1, 3, 4]
    """
```

I'll just provide the full code.

Let's verify time complexity: O(N) for counting, O(N) for filtering. Total O(N). Space O(N). This is optimal.

One thing to consider: sometimes HumanEval problems expect standard library only, but `collections` is standard. It's fine. Alternatively, I could use a dictionary manually, but `Counter` is cleaner.

I will stick with `Counter`.

Code structure:
```python
from typing import List
from collections import Counter

def remove_duplicates(numbers: List[int]) -> List[int]:
    counts = Counter(numbers)
    return [num for num in numbers if counts[num] == 1]
```

Check if any specific formatting is required. The prompt says "Implement a file **`solution.py`** that completes the function below."
I will output the code block.

One minor point: `from collections import Counter` might not be strictly necessary if I just use a dict, but it's standard. I'll include it.

Let's test mentally:
`numbers = [1, 2, 3, 2, 4]`
`counts = {1:1, 2:2, 3:1, 4:1}`
`[num for num in numbers if counts[num] == 1]` -> `[1, 3, 4]`
Matches example.

All good.
I will produce the solution.
One detail: The prompt includes `from typing import List` at the top. I'll keep it.
I'll write out the full file content.
Done. 
Let's generate. 
Self-Correction/Verification during thought: 
Is there any chance "remove all elements that occur more than once" means something else? No, it's standard.
Could there be a case where `numbers` is large? O(N) is fine.
The function signature matches.
I'll output exactly what's requested.
Code:
```python
from typing import List
from collections import Counter

def remove_duplicates(numbers: List[int]) -> List[int]:
    counts = Counter(numbers)
    return [num for num in numbers if counts[num] == 1]
```
This is correct and concise.
Proceeds. 
Output matches request.✅
Note: I'll make sure to include the imports as requested. The prompt already has `from typing import List`, so I'll just add `from collections import Counter` or implement without it to be safe, but `Counter` is perfectly fine. I'll stick with `Counter`.
Actually, to be extremely safe with imports, I can just use a standard dict:
```python
from typing import List

def remove_duplicates(numbers: List[int]) -> List[int]:
    counts = {}
    for num in numbers:
        counts[num] = counts.get(num, 0) + 1
    return [num for num in numbers if counts[num] == 1]
```
This avoids extra imports and is just as clean. I'll go with this to be strictly within standard library without extra imports, though `collections` is standard. Either is fine. I'll stick to `Counter` for readability, it's Pythonic. Actually, many coding platforms prefer minimal imports. I'll use `Counter` as it's idiomatic.

Wait, the prompt says "Implement a file solution.py that completes the function below."
I will provide the full code.

Final check of the prompt: "Keep the given name and signature; your file must define it at module level."
All good.
Output matches.✅
Proceeds. 
Generating response. 
```python
from typing import List
from collections import Counter

def remove_duplicates(numbers: List[int]) -> List[int]:
    counts = Counter(numbers)
    return [num for num in numbers if counts[num] == 1]
```
This is correct. I will output it. 
One minor thing: sometimes `collections` isn't imported in the stub. I'll add it. It's fine.
Done. 
Output matches request. 
Proceeds. 
[Output Generation] -> *Self-Correction/Refinement during generation prep*: 
I'll just provide the exact code block. No extra text.
The prompt asks for `solution.py`.
I will wrap it in ```python ... ```.
Ready. 
Output Generation. 
```python
from typing import List
from collections import Counter

def remove_duplicates(numbers: List[int]) -> List[int]:
    counts = Counter(numbers)
    return [num for num in numbers if counts[num] == 1]
```
Looks solid.✅
Done. 
[Final Check]
Input: `[1, 2, 3, 2, 4]`
Counts: `{1: 1, 2: 2, 3: 1, 4: 1}`
Result: `[1, 3, 4]`
Matches docstring.
Complexity: O(N) time, O(N) space.
Order preserved: Yes.
Signature matches: Yes.
Module level: Yes.
All constraints met.
Proceeds. 
[Output Generation] (matches the final code block)
Done. 
(Self-Correction/Note during thought: I'll make sure to include `from typing import List` as given, and add `from collections import Counter`. It's standard.)
All good. 
Output matches. 
[Done]