Merge pull request #241 from ikostan/exercism-sync/ac010ff38964c0eb

Exercism sync/ac010ff38964c0eb

Author: ikostan

solutions/python/flower-field/3/flower_field.py

@@ -0,0 +1,191 @@
+"""
+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
+directly adjacent (horizontally, vertically, diagonally) to each square.
+"""
+
+
+def annotate(garden: list) -> list:
+    """
+    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
+    :raises ValueError: If the garden is non-rectangular or contains
+                        invalid characters.
+    """
+    # empty list
+    if not garden:
+        return []
+
+    # when the board receives malformed input
+    if not _is_garden_valid(garden):
+        raise ValueError("The board is invalid with current input.")
+
+    for i_row, row in enumerate(garden):
+        for i_col, char in enumerate(row):
+            if char == " ":
+                flower_count: int = 0
+                flower_count += _calc_flower_top(i_row, i_col, garden)
+                flower_count += _calc_flower_bottom(i_row, i_col, garden)
+                flower_count += _calc_flower_left(i_row, i_col, garden)
+                flower_count += _calc_flower_right(i_row, i_col, garden)
+
+                if flower_count != 0:
+                    garden[i_row] = (
+                        garden[i_row][:i_col]
+                        + str(flower_count)
+                        + garden[i_row][i_col + 1:]
+                    )
+    return garden
+
+
+def _calc_flower_left(i_row: int, i_col: int, garden: list) -> int:
+    """
+    Count contiguous flowers to the left of the current position.
+
+    Scans leftward from ``(i_row, i_col - 1)`` until a non-flower character is
+    found or the row boundary is reached.
+
+    :param int i_row: Current row index.
+    :param int i_col: Current column index.
+    :param list garden: The garden as a list of strings.
+    :returns: Number of adjacent ``*`` cells to the left.
+    :rtype: int
+    """
+    flower_count: int = 0
+
+    if i_col - 1 >= 0:
+        for char in garden[i_row][:i_col][::-1]:
+            if char == "*":
+                flower_count += 1
+            else:
+                break
+    return flower_count
+
+
+def _calc_flower_right(i_row: int, i_col: int, garden: list) -> int:
+    """
+    Count contiguous flowers to the right of the current position.
+
+    Scans rightward from ``(i_row, i_col + 1)`` until a non-flower character is
+    found or the row boundary is reached.
+
+    :param int i_row: Current row index.
+    :param int i_col: Current column index.
+    :param list garden: The garden as a list of strings.
+    :returns: Number of adjacent ``*`` cells to the right.
+    :rtype: int
+    """
+    flower_count: int = 0
+
+    if i_col + 1 < len(garden[i_row]):
+        for char in garden[i_row][i_col + 1:]:
+            if char == "*":
+                flower_count += 1
+            else:
+                break
+    return flower_count
+
+
+def _calc_flower_top(i_row: int, i_col: int, garden: list) -> int:
+    """
+    Count flowers in the three cells directly above the current position.
+
+    Checks the top-left, top, and top-right neighbors when the row above
+    exists and contains any flowers.
+
+    :param int i_row: Current row index.
+    :param int i_col: Current column index.
+    :param list garden: The garden as a list of strings.
+    :returns: Number of ``*`` cells among the three upper neighbors.
+    :rtype: int
+    """
+
+    flower_count: int = 0
+
+    if i_row - 1 >= 0 and "*" in garden[i_row - 1]:
+        # top-left
+        if i_col > 0 and garden[i_row - 1][i_col - 1] == "*":
+            flower_count += 1
+        # top
+        if garden[i_row - 1][i_col] == "*":
+            flower_count += 1
+        # top-right
+        if (
+            i_col + 1 < len(garden[i_row])
+            and garden[i_row - 1][i_col + 1] == "*"
+        ):
+            flower_count += 1
+    return flower_count
+
+
+def _calc_flower_bottom(i_row: int, i_col: int, garden: list) -> int:
+    """
+    Count flowers in the three cells directly below the current position.
+
+    Checks the bottom-left, bottom, and bottom-right neighbors when the row
+    below exists and contains any flowers.
+
+    :param int i_row: Current row index.
+    :param int i_col: Current column index.
+    :param list garden: The garden as a list of strings.
+    :returns: Number of ``*`` cells among the three lower neighbors.
+    :rtype: int
+    """
+
+    flower_count: int = 0
+
+    if i_row + 1 < len(garden) and "*" in garden[i_row + 1]:
+        # bottom-left
+        if i_col > 0 and garden[i_row + 1][i_col - 1] == "*":
+            flower_count += 1
+        # bottom
+        if garden[i_row + 1][i_col] == "*":
+            flower_count += 1
+        # bottom-right
+        if (
+            i_col + 1 < len(garden[i_row])
+            and garden[i_row + 1][i_col + 1] == "*"
+        ):
+            flower_count += 1
+    return flower_count
+
+
+def _is_garden_valid(garden: list) -> bool:
+    """
+    Check whether the garden input is a valid rectangular board.
+
+    A garden is considered valid when all rows have the same length and only
+    contain spaces or ``*`` characters.
+
+    :param list garden: Candidate garden as a list of strings.
+    :returns: ``True`` if the input is rectangular and uses only valid
+              characters; otherwise ``False``.
+    :rtype: bool
+    """
+
+    garden_length: int = len(garden[0])
+    # when the board receives malformed input
+    for row in garden:
+        # garden is not a rectangle due to inconsistent row length
+        if len(row) != garden_length:
+            return False
+        # contains invalid chars inside row
+        valid_chars: bool = all(char in " *" for char in row)
+        if not valid_chars:
+            return False
+    return True