From 4cb5059fc235be4c3da665559207f771307b4e95 Mon Sep 17 00:00:00 2001
From: DannyAbdi <dannyabdi13@gmail.com>
Date: Fri, 8 Mar 2024 01:44:40 +0000
Subject: [PATCH] Modified minmax algorithm to incorporate alpha beta pruning
---
minmax.py | 27 ++++++++++++++++-----------
1 file changed, 16 insertions(+), 11 deletions(-)
diff --git a/minmax.py b/minmax.py
index e991a2f..cb745b9 100644
--- a/minmax.py
+++ b/minmax.py
@@ -34,37 +34,42 @@ class MinMax:
self.maze.current_level[y][x] != 1)
"""
- Performs the MinMax algorithm to determine the best move the enemy can take.
+ Performs the MinMax algorithm with Alpha-beta pruning to determine the best move the enemy can take.
:param player_position: The current position of the player agent.
:param enemy_position: The current position of the enemy agent.
:param depth: The depth of the MinMax search tree.
- :param maximising_player: True if maximising player (enemy), False if minimising player (player).
+ :param alpha: The best value that the maximizing player currently can guarantee.
+ :param beta: The best value that the minimizing player currently can guarantee.
+ :param maximizing_player: True if maximizing player (enemy), False if minimizing player (player).
:return: The best move for the enemy agent.
"""
- def minmax(self, player_position, enemy_position, depth, maximising_player):
+ def minmax(self, player_position, enemy_position, depth, alpha, beta, maximizing_player):
if depth == 0 or self.game_over():
# Evaluate the current game state
return self.evaluate(player_position, enemy_position)
- if maximising_player:
+ if maximizing_player:
max_eval = float('-inf')
valid_moves = self.get_valid_moves(enemy_position)
- best_move = None
for move in valid_moves:
if self.is_valid_move(move):
- eval = self.minmax(player_position, move, depth - 1, False)
- if eval > max_eval:
- max_eval = eval
- best_move = move
- return max_eval if depth == 1 else best_move
+ eval = self.minmax(player_position, move, depth - 1, alpha, beta, False)
+ max_eval = max(max_eval, eval)
+ alpha = max(alpha, eval)
+ if beta <= alpha:
+ break
+ return max_eval
else:
min_eval = float('inf')
valid_moves = self.get_valid_moves(player_position)
for move in valid_moves:
if self.is_valid_move(move):
- eval = self.minmax(move, enemy_position, depth - 1, True)
+ eval = self.minmax(move, enemy_position, depth - 1, alpha, beta, True)
min_eval = min(min_eval, eval)
+ beta = min(beta, eval)
+ if beta <= alpha:
+ break
return min_eval
"""
--
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