Alpha Beta Search Pseudocode

Alpha Beta Search Pseudocode.py

def next-move(state, depth):
  bestMove = nil
  alpha = -INF
  for next-state in state.nexts():
    result = minscore(next-state, depth-1, alpha, INF)
    if result > alpha:
      alpha = result
      bestMove = next-state.move()
    if alpha >= MAX-POSSIBLE-SCORE:
      break
  return bestMove
	
def maxscore(state, depth, alpha, beta):
  if isTerminal(state):
    return goal-value(state)
  if depth <= 0: 	
    return heuristic-value(state)     
  for next-state in state.nexts(): 	
    score = minscore(next, depth-1, alpha, beta) 	
    alpha = max(alpha, score) 	
    if alpha >= beta:
      return beta
  return alpha

def minscore(state, depth, alpha, beta):
  if isTerminal(state):
    return goal-value(state)
  if depth <= 0: 	
    return heuristic-value(state)     
  for next-state in state.nexts():  	
    score = maxscore(next, depth-1, alpha, beta) 	
    beta = min(beta, score) 	
    if alpha >= beta:
      return alpha
  return beta