Queen Attack2026-04-29

My Solution: Exercism Queen Attack solution

Instructions

Determine if two queens on a chessboard can attack each other.

Rules:

• Queens are on an 8x8 board with coordinates 0 to 7.
• Raise ValueError with appropriate messages for invalid positions (not positive, not on board).
• Raise ValueError if both queens are in the same square.
• Queens can attack horizontally, vertically, or diagonally.

Solution

class Queen:
    def __init__(self, row, column):
        if row < 0:
            raise ValueError("row not positive")
        if row > 7:
            raise ValueError("row not on board")
        if column < 0:
            raise ValueError("column not positive")
        if column > 7:
            raise ValueError("column not on board")
            
        self.row = row 
        self.column = column
        
    def can_attack(self, another_queen):
        if self.row == another_queen.row and self.column == another_queen.column:
            raise ValueError("Invalid queen position: both queens in the same square")

        return (
            self.row == another_queen.row or 
            self.column == another_queen.column or 
            abs(another_queen.row - self.row) == abs(another_queen.column - self.column)
        )

Syntax Notes

• Validation happens in __init__ so invalid positions are caught at construction time.
• can_attack() first checks for the same-square edge case.
• Same row: self.row == another_queen.row
• Same column: self.column == another_queen.column
• Diagonal: the absolute differences in row and column are equal.