Merge pull request #269 from ikostan/exercism-sync/80e487be7475263f

Exercism sync/80e487be7475263f

Author: ikostan

solutions/python/flower-field/17/flower_field.py

@@ -0,0 +1,128 @@
+"""
+Flower Field is a compassionate reimagining of the popular game Minesweeper.
+
+This module provides helpers to validate and annotate a rectangular garden
+representation, where each row is a string comprised of spaces and ``*``
+characters. A ``*`` denotes a flower; a space denotes an empty square.
+
+The goal is to compute numeric hints indicating how many flowers are
+adjacent (horizontally, vertically, diagonally) to each square.
+"""
+
+# Relative offsets to the eight neighboring cells around a given position
+COORDINATES: tuple[tuple[int, int]] = (
+    (-1, -1),
+    (-1, 0),
+    (-1, 1),
+    (0, -1),
+    (0, 1),
+    (1, -1),
+    (1, 0),
+    (1, 1),
+)
+
+
+def annotate(garden: list[str]) -> list[str]:
+    """
+    Annotate a garden with counts of adjacent flowers.
+
+    Expects a rectangular list of strings containing only spaces and ``*``.
+    Validation errors raise a :class:`ValueError`.
+
+    :param list garden: A list of equal-length strings representing the garden.
+        ``*`` marks a flower; space marks empty.
+    :returns: An annotated garden of the same shape. Empty squares are
+        replaced by digits (``"1"``–``"8"``) when adjacent to flowers;
+        squares with zero adjacent flowers remain spaces. Flowers
+        (``*``) are preserved.
+    :rtype: list[str]
+    :raises ValueError: If the garden is non-rectangular or contains
+        invalid characters.
+    """
+    # empty list
+    if not garden:
+        return []
+    # raise an error when the board receives malformed input
+    _validate(garden)
+    return [
+        "".join(
+            str(count)
+            if (count := _calc_surrounding_flowers(i_row, i_col, garden)) != 0
+            else char
+            for i_col, char in enumerate(row)
+        )
+        for i_row, row in enumerate(garden)
+    ]
+
+
+def _calc_surrounding_flowers(i_row: int, i_col: int, garden: list[str]) -> int:
+    """
+    Count flowers adjacent to the given cell.
+
+    Counts the eight neighboring positions around ``(i_row, i_col)`` when the
+    current cell is empty (space). If the cell itself is a flower (``*``), the
+    count remains zero as the caller preserves flowers unchanged.
+
+    :param int i_row: Row index of the target cell.
+    :param int i_col: Column index of the target cell.
+    :param list garden: The rectangular garden representation.
+    :returns: Number of adjacent flowers (0–8).
+    :rtype: int
+    """
+    return (
+        sum(
+            _process_cell(i_row, offset_row, i_col, offset_col, garden)
+            for offset_row, offset_col in COORDINATES
+        )
+        if garden[i_row][i_col] == " "
+        else 0
+    )
+
+
+def _process_cell(i_row, offset_row, i_col, offset_col, garden) -> int:
+    """
+    Return 1 if the neighbor at the given relative offset contains a flower.
+
+    Computes the absolute coordinates from ``(i_row, i_col)`` and the provided
+    offsets, performs bounds checking to avoid ``IndexError``, and returns ``1``
+    only when the cell is within the garden and equals ``"*"``.
+
+    :param int i_row: Row index of the reference cell.
+    :param int offset_row: Row delta to apply to ``i_row``.
+    :param int i_col: Column index of the reference cell.
+    :param int offset_col: Column delta to apply to ``i_col``.
+    :param list garden: The rectangular garden representation.
+    :returns: ``1`` when the computed neighbor cell contains a flower, otherwise ``0``.
+    :rtype: int
+    """
+    row: int = i_row + offset_row
+    col: int = i_col + offset_col
+
+    if (
+        0 <= row < len(garden)  # ROW: Avoid IndexError
+        and 0 <= col < len(garden[0])  # COL: Avoid IndexError
+        and garden[row][col] == "*"  # Detect/count flower
+    ):
+        return 1
+    return 0
+
+
+def _validate(garden: list[str]) -> None:
+    """
+    Validate the garden shape and contents.
+
+    Ensures the input is rectangular and contains only spaces and ``*``.
+    Raise ValueError when the board receives malformed input garden is not
+    a rectangle due to inconsistent row length or contains invalid chars
+    inside the row.
+
+    :param list garden: A list of equal-length strings to validate.
+    :raises ValueError: If rows have differing lengths or contain characters
+        other than space or ``*``.
+    """
+    garden_length = len(garden[0])
+    if any(
+        (len(row) != garden_length or not all(char in " *" for char in row))
+        for row in garden
+    ):
+        raise ValueError("The board is invalid with current input.")