NQueens

This game is the classical N-Queens puzzle. The objective of the game is to place N queens on a N x N chessboard so that no two queens attack each other. The attack of the queens follows the rules of chess: a queen can attack horizontally, vertically and diagonally.

The game has a chessboard (square grid) of N x N squares. Each movement indicates the place of a new queen in the chessboard. After N movements, the optimal score is reached when no queens attack each other.

Goal

After placing N queens on a N x N chessboard, the queens must attack as less other queens as possible.

Score

+1 for each queen in the range of attack of other queen. This will always give even scores.

Import

from IArena.games.NQueens import NQueensPosition
from IArena.games.NQueens import NQueensMovement
from IArena.games.NQueens import NQueensRules

Movement

A movement is represented by a tuple new_position of 2 int:

new_position
- tuple(int, int)
  
  int
  
  0 <= tower_source < N
  
  Number of row to place the next queen.
- tuple(int, int)
  
  int
  
  0 <= tower_source < N
  
  Number of column to place the next queen.

movement = NQueensMovement(new_position=[0, 0])

Position

A position is represented by an int describing the size of the board, and a list of movements. Each movement represents the position of a queen in the board.

# position : NQueensPosition
position.n                  # The size of the board is n x n
len(position.positions)     # Number of queens already in the board
position.positions[0][0]    # Row of the first queen
position.positions[-1][1]   # Column of the last queen

Rules

Remember that using score method can give the current result of the game:

# rules     : NQueensRules
# position  : NQueensPosition
rules.score(position)   # Returns how many queens are attacking each other

Constructor

Can receive an argument n : int that represents the size of the board.

# Initial board of 8x8
rules = nqueensRules()

# Initial board of 5x5
rules = nqueensRules(n=5)