#!/usr/bin/python
#
# http://home.chello.no/~dudley/
#
from constraint import *
import sys

STUDENTDESKS = [[  0,  1,  0,  0,  0,  0],
                [  0,  2,  3,  4,  5,  6],
                [  0,  7,  8,  9, 10,  0],
                [  0, 11, 12, 13, 14,  0],
                [ 15, 16, 17, 18, 19,  0],
                [  0,  0,  0,  0, 20,  0]]

def main():
    problem = Problem()
    problem.addVariables(range(1,21), ["A", "B", "C", "D", "E"])
    problem.addConstraint(SomeInSetConstraint(["A"], 4, True))
    problem.addConstraint(SomeInSetConstraint(["B"], 4, True))
    problem.addConstraint(SomeInSetConstraint(["C"], 4, True))
    problem.addConstraint(SomeInSetConstraint(["D"], 4, True))
    problem.addConstraint(SomeInSetConstraint(["E"], 4, True))
    for row in range(len(STUDENTDESKS)-1):
        for col in range(len(STUDENTDESKS[row])-1):
            lst = [STUDENTDESKS[row][col], STUDENTDESKS[row][col+1],
                   STUDENTDESKS[row+1][col], STUDENTDESKS[row+1][col+1]]
            lst = [x for x in lst if x]
            problem.addConstraint(AllDifferentConstraint(), lst)
    showSolution(problem.getSolution())

def showSolution(solution):
    for row in range(len(STUDENTDESKS)):
        for col in range(len(STUDENTDESKS[row])):
            id = STUDENTDESKS[row][col]
            sys.stdout.write(" %s" % (id and solution[id] or " "))
        sys.stdout.write("\n")

if __name__ == "__main__":
    main()