Sudoku Solver.py

from copy import deepcopy

SIZE = 5
ITEMS = SIZE * SIZE

table = [
  [-1, -1, -1, -1, -1],
  [-1, -1, -1, -1, -1],
  [-1, -1, -1, -1, -1],
  [-1, -1, -1, -1, -1],
  [-1, -1, -1, -1, -1],
]


def print_table(table):
  for y in table:
    print(', '.join([ str(i+1) if i != -1 else '_' for i in y ]))


class TableSolver:
  def __init__(self) -> None:
    self.orig_table = [ [-1]*SIZE for _ in range(SIZE)]
    self.table = [ [-1]*SIZE for _ in range(SIZE)]
    self.idx = 0
    self.last_backed = False

  @property
  def orig_item(self):
    return self.orig_table[self.idx // SIZE][self.idx % SIZE]
  
  @property
  def item(self):
    return self.table[self.idx // SIZE][self.idx % SIZE]

  @item.setter
  def item(self, x):
    self.table[self.idx // SIZE][self.idx % SIZE] = x
  
  @property
  def is_given(self):
    return self.orig_table[self.idx // SIZE][self.idx % SIZE] != -1
  
  def travel(self):
    self.idx = self.idx + 1
    self.last_backed = False
  
  def back(self):
    self.idx = self.idx - 1
    self.last_backed = True
  
  def find_next_num(self):
    choices = set(range(SIZE))
    choices.difference_update(self.table[self.idx // SIZE])
    choices.difference_update([self.table[y][self.idx % SIZE] for y in range(SIZE)])
    choices = [x for x in choices if x > self.item]
    if len(choices) == 0:
      return None
    return min(choices)
  
  def solve(self, table):
    self.orig_table = deepcopy(table)
    self.table = deepcopy(self.orig_table)
    while self.idx < ITEMS:
      if self.is_given:
        if self.last_backed:
          self.back()
        else:
          self.travel()
      else:
        next_num = self.find_next_num()
        if next_num == None:
          self.item = -1
          self.back()
        else:
          self.item = next_num
          self.travel()
    return deepcopy(self.table)


table = TableSolver().solve(table)
print_table(table)