My program uses the minimax-algorithm to choose the most otimal move against the human player in tic-tac-toe. (this is working)
After that I tried to implement the alpha-beta-pruning to optimize the time the algorithm needs in order to get the optimal move. (this doesnt work)
I know why the Error is raised, but I dont get why the Error is raised by 'alpha' and 'beta' and not by 'board' or 'minX' or 'minY' too.
I think the Variables I declared should all be global variables, should they?
Error: UnboundLocalError: local Variable 'beta' referenced before assignment
#Global Variables
values = [0,1,2]
minX = 0
minY = 0
alpha = -999
beta = 999
global alpha
global beta
board = [["-" for x in range(3)] for y in range(3)]
#ausgabe
def ausgabe():
for zeile in range(3):
for spalte in range(3):
print("|"+str(board[zeile][spalte]),end="")
print("|")
#auswertung
#liefert 0, wenn O gewonnen hat
#liefert 2, wenn X gewonnen hat
#liefert 1, wenn es unentschieden ausgeht
#liefert -1 wenn noch nicht klar
def auswertung():
for i in ("X", "O"):
for x in range(3):
if board[x][0] == i and board[x][1] == i and board[x][2] == i:
return i
for y in range(3):
if board[0][y] == i and board[1][y] == i and board[2][y] == i:
return i
if board[0][0] == i and board[1][1] == i and board[2][2] == i:
return i
if board[0][2] == i and board[1][1] == i and board[2][0] == i:
return i
for zeile in range(3):
for spalte in range(3):
if board[zeile][spalte] == "-":
return -1
return 1
#max
def max():
temp = auswertung()
if temp != -1:
if temp == "X":
return 2
elif temp == "O":
return 0
else:
return temp
maximalwert = -999
for x in range(3):
for y in range(3):
if board[x][y] == "-":
board[x][y] = "X"
temp = alpha
alpha = beta
beta = temp
if alpha < beta:
break
wert = min()
board[x][y] = "-"
if wert > maximalwert:
maximalwert = wert
return maximalwert
#min
def min():
temp = auswertung()
if temp != -1:
if temp == "X":
return 2
elif temp == "O":
return 0
else:
return temp
minimalwert = 999
for x in range(3):
for y in range(3):
if board[x][y] == "-":
board[x][y] = "O"
temp = beta
beta = alpha
alpha = temp
if alpha > beta:
break
wert = max()
board[x][y] = "-"
if wert < minimalwert:
minimalwert = wert
return minimalwert
#wo befindet sich das min
def minWo():
temp = auswertung()
if temp != -1:
if temp == "X":
return 2
elif temp == "O":
return 0
else:
return temp
global minX
global minY
minimalwert = 999
for x in range(3):
for y in range(3):
if board[x][y] == "-":
board[x][y] = "O"
temp = beta
beta = alpha
alpha = temp
if alpha > beta:
break
wert = max()
board[x][y] = "-"
if wert < minimalwert:
minX = x
minY = y
minimalwert = wert
return minimalwert
def user_input():
while True:
try:
number1 = int(input("number1: "))
number2 = int(input("number2: "))
if number1 in values and number2 in values:
if board[number1][number2] == "-":
return number1, number2
else:
print("Invalid Input!\ttry again")
except ValueError:
print("Invalid Input!\ttry again")
def game_still_going():
winner = auswertung()
if winner == "X" or winner == "O":
print("Player "+winner+" won the game")
return False
elif winner == 1:
print("It's a draw")
return False
return True
def play_game():
while game_still_going():
number1,number2 = user_input()
board[number1][number2] = "X"
minWo()
board[minX][minY] = "O"
ausgabe()
play_game()
