L12Q8_Sudoku.py

# THREE GOLD STARS

# Sudoku [http://en.wikipedia.org/wiki/Sudoku]
# is a logic puzzle where a game
# is defined by a partially filled
# 9 x 9 square of digits where each square
# contains one of the digits 1,2,3,4,5,6,7,8,9.
# For this question we will generalize
# and simplify the game.

# Define a procedure, check_sudoku,
# that takes as input a square list
# of lists representing an n x n
# sudoku puzzle solution and returns the boolean
# True if the input is a valid
# sudoku square and returns the boolean False
# otherwise.

# A valid sudoku square satisfies these
# two properties:

#   1. Each column of the square contains
#       each of the whole numbers from 1 to n exactly once.

#   2. Each row of the square contains each
#       of the whole numbers from 1 to n exactly once.

# You may assume the the input is square and contains at
# least one row and column.

correct = [[1,2,3],
           [2,3,1],
           [3,1,2]]

incorrect = [[1,2,3,4],
             [2,3,1,3],
             [3,1,2,3],
             [4,4,4,4]]

incorrect1 = [[1,2,1,4],
             [2,3,1,3],
             [3,1,2,3],
             [4,4,4,4]]

incorrect2 = [[1,2,3,4],
             [2,3,1,4],
             [4,1,2,3],
             [3,4,1,2]]

#see the six on [1]
incorrect3 = [[1,2,3,4,5],
              [2,3,1,5,6],
              [4,5,2,1,3],
              [3,4,5,2,1],
              [5,6,4,3,2]]

incorrect4 = [['a','b','c'],
              ['b','c','a'],
              ['c','a','b']]

incorrect5 = [ [1, 1.5],
               [1.5, 1]]

test1 = [2,3,1,5,6]
test2 = [1,2,3,4]
test3 = [1,2,1,4]
test4 =[4,5,2,1,3]
test5 =[1, 2, 4, 3]
#checks for repeated numbers in a list and range of 1:length

def check_sudoku(matrix):
    n = len(matrix)
    digit = 1
    while digit <= n:
        i = 0
        while i < n:
            rowCount = 0
            columnCount = 0
            j = 0
            while j < n: #for each entry in nth row/column
                if matrix[i][j] == digit:
                    rowCount += 1
                if matrix[j][i] == digit:
                    columnCount += 1
                j += 1
            if rowCount != 1 or columnCount != 1:
                return 'False'
            i += 1 #next row/column
        digit += 1        #next digit
    return True


print check_sudoku(correct)
#>>> True

print check_sudoku(incorrect1)
#>>> False

print check_sudoku(incorrect)
#>>> False

print check_sudoku(incorrect2)
#>>> False

print check_sudoku(incorrect3)
#>>> False

print check_sudoku(incorrect5)
#>>> False

#print check_sudoku(incorrect4)
#>>> False