testBackTracking.py

from classes import *
from startScreen import *
import copy

def findCellsWithLeastPossibleLegal(board):
    leastlen = 9
    for row in range(9):
        for col in range(9):
            if (len(Input.getLegalValue(board)[(row, col)]) < leastlen and 
                (Input.getNumber(board, row, col) == 0)):
                leastlen = len(Input.getLegalValue(board)[(row, col)])
                least = (row, col)
    return least

#From 8.17 solveMiniSudoku
def backtracking(app, board): 
    result = Input(copy.deepcopy(app.initialBoard))
    solution = helper(board, result)
    return solution

def helper(board, result):
    if isThereEmptyCell(result) == False:
        return result
    
    if findCellsWithLeastPossibleLegal(result) == None: 
        return None
    
    else:
        row, col = findCellsWithLeastPossibleLegal(result)
        val = Input.getLegalValue(result)[(row, col)]
        for num in val:
            Input.putNumberIn(result, row, col, num)
            solution = helper(board,result)
            if solution != None:
                    return solution
            Input.putNumberIn(result, row, col, 0)
    return None

def isThereEmptyCell(board):
    rows, cols = 9, 9 
    result = []
    for row in range(rows):
        for col in range(cols):
            if Input.getNumber(board, row, col) == 0:
                return True
    return False