Sudoku
class Sudoku
def initialize
@field = Hash.new()
@visited_nums = Hash.new()
end

def empty_field # creating empty sudoku 9x9 field
i = 1
while i<10
j = 1
while j<10
cell_key = [i,j]
@field[cell_key] = nil
j+=1
end
i+=1
end
end

def visited_numbers # creating empty arrays for already checked & invalid numbers for each cell
i = 1
while i<10
j = 1
while j<10
cell_key = [i,j]
@visited_nums[cell_key] = []
j+=1
end
i+=1
end
end

def check_column(pick, row) # checking the column
for c in 1..9
if @field[[row, c]] == pick
return false
end
end
return true
end

def check_row(pick, column) # checking the row
for r in 1..9
if @field[[r, column]] == pick
return false
end
end
return true
end

def check_segment(pick, row, column) # checking the 3x3 square
if column<=3
if row<=3
for i in 1..3
for j in 1..3
if @field[[i, j]] == pick
return false
end
end
end
elsif row>3 && row<=6
for i in 3..6
for j in 1..3
if @field[[i, j]] == pick
return false
end
end
end
elsif row>6 && row<=9
for i in 6..9
for j in 1..3
if @field[[i, j]] == pick
return false
end
end
end
end
elsif column>3 && column<=6
if row<=3
for i in 1..3
for j in 3..6
if @field[[i, j]] == pick
return false
end
end
end
elsif row>3 && row<=6
for i in 3..6
for j in 3..6
if @field[[i, j]] == pick
return false
end
end
end
elsif row>6 && row<=9
for i in 6..9
for j in 3..6
if @field[[i, j]] == pick
return false
end
end
end
end
elsif column>6 && column<=9
if row<=3
for i in 1..3
for j in 6..9
if @field[[i, j]] == pick
return false
end
end
end
elsif row>3 && row<=6
for i in 3..6
for j in 6..9
if @field[[i, j]] == pick
return false
end
end
end
elsif row>6 && row<=9
for i in 6..9
for j in 6..9
if @field[[i, j]] == pick
return false
end
end
end
end
end
return true
end

def create_field # generating solved puzzle
empty_field
visited_numbers
i = 1
while i<=9 # i - row counter
j = 1
marks_index = 8
marks = [1,2,3,4,5,6,7,8,9]
while j<=9 # j - column counter
pick = marks[rand(0..marks_index)]
if check_column(pick, i) && check_row(pick, j) && check_segment(pick, i, j)
@field[[i,j]] = pick
@visited_nums[[i,j]].push(pick)
j+=1
end
end
i+=1
puts ''
end

end

def show_field
i = 1
while i<10
j = 1
while j<10
#if @field[[i,j]] == nil
# @field[[i,j]] == ' '
#end
if j==4 || j==7
print '| '
end
if j%9==0
print "#{@field[[i,j]]} "
puts ''
if i==3 || i==6
for k in 0..8
print '--'
end
print '---'
puts "\n"
end
else
print "#{@field[[i,j]]} "
end
j+=1
end
i+=1
end
end

end

sudoku = Sudoku.new
puts ''
sudoku.create_field
puts ''
sudoku.show_field