sudoku

board=[

    [2,3,0,0,7,0,0,0,0],

    [6,0,0,1,9,5,0,0,0],

    [0,9,8,0,0,0,0,6,0],

    [8,0,0,0,6,0,0,0,3],

    [4,0,0,8,0,3,0,0,1],

    [5,0,0,0,2,0,0,0,6],

    [0,6,0,0,0,0,2,8,0],

    [0,0,0,4,1,9,0,0,5],

    [0,0,0,0,9,0,0,8,9]]

def print_board(bo):

    for i in range(len(bo)):

        if i%3 == 0 and i!=0:

            print("---------------------")

        for j in range(len(bo[0])):

            if j%3 == 0 and j!=0:

                print(" | ", end ="")

            if j==8:

                print(bo[i][j])

            else:

                print(str(bo[i][j]) + " ",end="")

def find_empty(bo):

    for i in range(len(bo)):

        for j in range(len(bo[0])):

            if bo[i][j] == 0:

                return (i, j)

    return None

def valid(bo, num, pos):

    for i in range(len(bo[0])):

        if bo[pos[0]][i] == num and pos[1]!= i:

            return False

    for j in range(len(bo)):

        if bo[i][pos[1]] == num and pos[0]!= i:

            return False

    box_x = pos[1]//3

    box_y = pos[0]//3

    for i in range(box_y*3, box_y*3 + 3):

        for j in range(box_x*3, box_x*3 + 3):

            if bo[i][j] == num and  (i,j) != pos:

                return False

    return True

def solve(bo):

    find = find_empty(bo)

    if not find:

        return True

    else:

        row, col = find

    for i in range(1,10):

        if valid(bo, i , (row,col)):

            bo[row][col] = i

            if solve(bo):

                return True

            bo[row][col]=0

    return False

print_board(board)

solve(board)

print("Solving")

print_board(board)

print("Solved")