7-6:三目並べ|紙とえんぴつで学ぶアルゴリズムとフローチャート

import random
import math

first = "○"
second = "×"
mark = {0 : "－", 1 : "", -1 : ""}
#1：プレイヤー、-1：コンピュータ

field = [[0, 0, 0], [0, 0, 0], [0, 0, 0]]
input_number = ["１", "２", "３", "４", "５", "６", "７", "８","９"]

def senkou_koukou():
  print("先攻（○）後攻（×）を決めます。")
  choice = int(input("0か1を入力してください。"))
  first_attack = random.randint(0, 1)

  print("先攻は " + str(first_attack) + "です。")

  if choice == first_attack:
    print("あなたは先攻です。")
    mark[1] = first
    mark[-1] = second
  else:
    print("あなたは後攻です。")
    mark[1] = second
    mark[-1] = first

  print(mark)

def print_field():
  str_line = ""

  print("")
  print("=====")
  for i in range(3):
    for j in range(3):
      if field[i][j] == 0:
        str_line += input_number[i * 3 + j]
      else:
        str_line += mark[field[i][j]]
      if j < 2:
        str_line += "｜"
    print(str_line)
    str_line = ""
    if i < 2:
      print("－＋－＋－")
  print("=====")
  print("")

def input_player(turn):
  print("表示されている番号のいずれかを入力してください。")
  while (True):
    input_str = input("")
    if input_str.isdigit():
      input_int = int(input_str)
      if input_int >= 1 and input_int <= 9:
        row = math.floor((input_int - 1) / 3)
        col = (input_int - 1) % 3
        if field[row][col] == 0:
          field[row][col] = 1
          break
    print("")
    print("もう一度、表示されている番号のいずれかを入力してください。")


def input_computer(turn):
  while (True):
    row = random.randint(0, 2)
    col = random.randint(0, 2)
    if field[row][col] == 0:
      print("コンピュータは " + str(row * 3 + col + 1) + " を選びました。" )
      field[row][col] = -1
      break

def check_winner(player_number):
  win = False
  for i in range(3):
    if sum(field[i]) == player_number * 3:
      win = True
      break
  if win == False:
    for j in range(3):
      if field[0][j] + field[1][j] + field[2][j] == player_number * 3:
        win = True
        break
  if win == False:
    if field[0][0] + field[1][1] + field[2][2] == player_number * 3:
      win = True
    elif field[2][0] + field[1][1] + field[0][2] == player_number * 3:
      win = True

  return win

def field_full():
  is_full = True
  for i in range(3):
    for j in range(3):
      if field[i][j] == 0:
        is_full = False
  return is_full

senkou_koukou()
print_field()

finish = False
turn = first
while (finish == False):

  if mark[1] == turn:
    input_player(turn)
    print_field()
    if check_winner(1) == True:
      print("あなたの勝ち")
      finish = True
  else:
    input_computer(turn)
    print_field()
    if check_winner(-1):
      print("あなたの負け")
      finish = True

  if finish == False and field_full() == True:
    print("引き分け")
    finish = True

  if turn == first:
    turn = second
  else:
    turn = first