he-009

# HumanEval/9

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, Tuple


def rolling_max(numbers: List[int]) -> List[int]:
    """ From a given list of integers, generate a list of rolling maximum element found until given moment
    in the sequence.
    >>> rolling_max([1, 2, 3, 2, 3, 4, 2])
    [1, 2, 3, 3, 3, 4, 4]
    """
```

<!-- imported from OpenAI HumanEval (HumanEval/9) -->

# Auto-generated from OpenAI HumanEval HumanEval/9. Do not edit by hand.
from solution import *  # noqa: F401,F403 (prompt helpers may be referenced by tests)
from solution import rolling_max as candidate

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


def check(candidate):
    assert candidate([]) == []
    assert candidate([1, 2, 3, 4]) == [1, 2, 3, 4]
    assert candidate([4, 3, 2, 1]) == [4, 4, 4, 4]
    assert candidate([3, 2, 3, 100, 3]) == [3, 3, 3, 100, 100]


def test_he_009():
    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, Tuple


def rolling_max(numbers: List[int]) -> List[int]:
    """ From a given list of integers, generate a list of rolling maximum element found until given moment
    in the sequence.
    >>> rolling_max([1, 2, 3, 2, 3, 4, 2])
    [1, 2, 3, 3, 3, 4, 4]
    """
    if not numbers:
        return []
    
    result = []
    current_max = numbers[0]
    for num in numbers:
        if num > current_max:
            current_max = num
        result.append(current_max)
    
    return result
```

The user wants me to implement the `rolling_max` function in Python.

Looking at the example:
- Input: `[1, 2, 3, 2, 3, 4, 2]`
- Output: `[1, 2, 3, 3, 3, 4, 4]`

The rolling maximum at each position is the maximum value seen so far (from the start up to and including that position).

Let me trace through:
- Position 0: max of [1] = 1
- Position 1: max of [1, 2] = 2
- Position 2: max of [1, 2, 3] = 3
- Position 3: max of [1, 2, 3, 2] = 3
- Position 4: max of [1, 2, 3, 2, 3] = 3
- Position 5: max of [1, 2, 3, 2, 3, 4] = 4
- Position 6: max of [1, 2, 3, 2, 3, 4, 2] = 4

So the algorithm is straightforward: iterate through the list, keeping track of the running maximum, and append it to the result.

Here's the implementation:

```python
from typing import List, Tuple


def rolling_max(numbers: List[int]) -> List[int]:
    """ From a given list of integers, generate a list of rolling maximum element found until given moment
    in the sequence.
    >>> rolling_max([1, 2, 3, 2, 3, 4, 2])
    [1, 2, 3, 3, 3, 4, 4]
    """
    if not numbers:
        return []
    
    result = []
    current_max = numbers[0]
    for num in numbers:
        if num > current_max:
            current_max = num
        result.append(current_max)
    
    return result
```

This is O(n) time and O(n) space for the result. Simple and correct.