Hi everyone I have this python code which works but is not optimal . Its a tic tac toe using minimax and alpha beta pruning .the computer is not selecting the third x and winning if it has the chance to but is placing it another spot which makes no sense . Can someone help me find out where my error is . Should i check winner before calling max node?

here is my code https://pastebin.com/z8mqnCeW

Please, post your code here in the forum, unless it's really big/complex with many files and is better to share a link to a repo

here is my code https://pastebin.com/z8mqnCeW

import turtle import copy import random screen = turtle.Screen() screen.setup(800,800) screen.title("Tic Tac Toe ") screen.setworldcoordinates(-5,-5,5,5) screen.bgcolor('light gray') screen.tracer(0,0) turtle.hideturtle() def draw_board(): turtle.pencolor('green') turtle.pensize(10) turtle.up() turtle.goto(-3,-1) turtle.seth(0) turtle.down() turtle.fd(6) turtle.up() turtle.goto(-3,1) turtle.seth(0) turtle.down() turtle.fd(6) turtle.up() turtle.goto(-1,-3) turtle.seth(90) turtle.down() turtle.fd(6) turtle.up() turtle.goto(1,-3) turtle.seth(90) turtle.down() turtle.fd(6) def draw_circle(x,y): turtle.up() turtle.goto(x,y-0.75) turtle.seth(0) turtle.color('red') turtle.down() turtle.circle(0.75, steps=100) def draw_x(x,y): turtle.color('blue') turtle.up() turtle.goto(x-0.75,y-0.75) turtle.down() turtle.goto(x+0.75,y+0.75) turtle.up() turtle.goto(x-0.75,y+0.75) turtle.down() turtle.goto(x+0.75,y-0.75) def draw_piece(i,j,p): if p==0: return x,y = 2*(j-1), -2*(i-1) if p==1: draw_x(x,y) else: draw_circle(x,y) def draw(b): draw_board() for i in range(3): for j in range(3): draw_piece(i,j,b[i][j]) screen.update() # return 1 if player 1 wins, 2 if player 2 wins, 3 if tie, 0 if game is not over def gameover(b): if b[0][0]>0 and b[0][0] == b[0][1] and b[0][1] == b[0][2]: return b[0][0] if b[1][0]>0 and b[1][0] == b[1][1] and b[1][1] == b[1][2]: return b[1][0] if b[2][0]>0 and b[2][0] == b[2][1] and b[2][1] == b[2][2]: return b[2][0] if b[0][0]>0 and b[0][0] == b[1][0] and b[1][0] == b[2][0]: return b[0][0] if b[0][1]>0 and b[0][1] == b[1][1] and b[1][1] == b[2][1]: return b[0][1] if b[0][2]>0 and b[0][2] == b[1][2] and b[1][2] == b[2][2]: return b[0][2] if b[0][0]>0 and b[0][0] == b[1][1] and b[1][1] == b[2][2]: return b[0][0] if b[2][0]>0 and b[2][0] == b[1][1] and b[1][1] == b[0][2]: return b[2][0] p = 0 for i in range(3): for j in range(3): p += (1 if b[i][j] > 0 else 0) if p==9: return 3 else: return 0 def play(x,y): global turn if turn=='x': return i = 3-int(y+5)//2 j = int(x+5)//2 - 1 if i>2 or j>2 or i<0 or j<0 or b[i][j]!=0: return if turn == 'x': b[i][j], turn = 1, 'o' else: b[i][j], turn = 2, 'x' draw(b) r = gameover(b) if r==1: screen.textinput("Game over!","X won!") elif r==2: screen.textinput("Game over!","O won!") elif r==3: screen.textinput("Game over!", "Tie!") if r>0: turtle.bye() _,move = max_node(b,-2,2) b[move[0]][move[1]] = 1 draw(b) r = gameover(b) if r==1: screen.textinput("Game over!","X won!") elif r==2: screen.textinput("Game over!","O won!") elif r==3: screen.textinput("Game over!", "Tie!") if r>0: turtle.bye() turn = 'o' b = [ [ 0,0,0 ], [ 0,0,0 ], [ 0,0,0 ] ] draw(b) turn = 'x' screen.onclick(play) #turtle.mainloop() def max_node(b,alpha,beta): r = gameover(b) if r==1: return 1,None elif r==2: return -1,None elif r==3: return 0,None score = -2 # find all possible next moves pm = list() for i in range(3): for j in range(3): if b[i][j] == 0: pm.append((i,j)) random.shuffle(pm) for (i,j) in pm: if b[i][j] == 0: nb = copy.deepcopy(b) nb[i][j] = 1 cs,_ = min_node(nb,alpha,beta) if score<cs: score=cs move = (i,j) alpha = max(alpha,cs) if alpha>=beta: return score,move return score,move def min_node(b,alpha,beta): r = gameover(b) if r==1: return 1,None elif r==2: return -1,None elif r==3: return 0,None score = 2 # find all possible next moves pm = list() random.shuffle(pm) for i in range(3): for j in range(3): if b[i][j] == 0: pm.append((i,j)) for (i,j) in pm: if b[i][j] == 0: nb = copy.deepcopy(b) nb[i][j] = 2 cs,_ = max_node(nb,alpha,beta) if score>cs: score=cs move = (i,j) beta = min(beta,cs) if alpha>=beta: return score,move return score,move _,move = max_node(b,-2,2) b[move[0]][move[1]] = 1 draw(b) turn = 1 screen.mainloop()

**buran**write Nov-28-2023, 08:56 AM:Please, post your code here in the forum, unless it's really big/complex with many files and is better to share a link to a repo