1. The problem statement, all variables and given/known data Code (Python): # Sudoku [[PLAIN]http://en.wikipedia.org/wiki/Sudoku][/PLAIN] [Broken] # 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]] incorrect2 = [[1,2,3,4], [2,3,1,4], [4,1,2,3], [3,4,1,2]] 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]] def check_sudoku(p): rows= coloums= t=0 for i in p: for e in i: if e not in rows: rows.append(e) else: return False rows= while t<=len(p): for i in p: if i.pop() not in coloums: coloums.append(i.pop()) else: return False coloums= t += 1 return True print check_sudoku(incorrect) #>>> False print check_sudoku(correct) #>>> True print check_sudoku(incorrect2) #>>> False print check_sudoku(incorrect3) #>>> False print check_sudoku(incorrect4) #>>> False print check_sudoku(incorrect5) #>>> False 2. Relevant equations 3. The attempt at a solution I dont actually want you to correct me, i just want for you to point out where i made the mistake as my code output gives all as False. I was sure it correctly checked everything, i have no idea why its behaving this way. The first part must be correct but the second might be the problem. Do you see the mistake?