improved the code

practice/minesweeper/minesweeper.py

@@ -1,13 +1,41 @@
 def annotate(minefield):
+    """
+    Annotate a minefield with the number of mines each square is adjacent to.
+
+    The minefield is represented as a list of strings. Each string represents a row of the minefield,
+    with '*' representing a mine and ' ' representing an empty square.
+
+    The function returns a new minefield where each empty square is replaced with the number of mines
+    that square is adjacent to. If a square is adjacent to no mines, it is replaced with a space.
+
+    Args:
+        minefield (list): A list of strings representing the minefield.
+
+    Returns:
+        list: A list of strings representing the annotated minefield.
+
+    Raises:
+        ValueError: If the minefield is not a rectangle or contains invalid characters.
+
+    Examples:
+        >>> annotate([" * ", "   ", " * "])
+        ['1*1', '232', '1*1']
+    """
+    # If the minefield is empty, return an empty list
     if not minefield:
         return []
 
+    # Check if the minefield is a rectangle and contains only valid characters
     if not all(len(row) == len(minefield[0]) for row in minefield) or any(c not in ' *' for row in minefield for c in row):
         raise ValueError("The board is invalid with current input.")
 
+    # Get the number of rows and columns in the minefield
     rows, cols = len(minefield), len(minefield[0])
+
+    # Initialize a 2D list to store the counts of adjacent mines
     counts = [[0]*cols for _ in range(rows)]
 
+    # For each square in the minefield, if it is a mine, increment the count of all adjacent squares
     for i in range(rows):
         for j in range(cols):
             if minefield[i][j] == '*':
@@ -16,6 +44,7 @@ def annotate(minefield):
                         if 0 <= i+di < rows and 0 <= j+dj < cols:
                             counts[i+di][j+dj] += 1
 
+    # Replace each count with a string, leaving mines as '*' and replacing 0 with ' '
     for i in range(rows):
         for j in range(cols):
             if minefield[i][j] == '*':
@@ -25,4 +54,5 @@ def annotate(minefield):
             else:
                 counts[i][j] = str(counts[i][j])
 
+    # Join each row into a string and return the annotated minefield
     return [''.join(row) for row in counts]