RPS

#Rock paper scissors with predictive AI
import random

def CPUPlay(choices, pastMoves):
    """CPUPlay() - generate computer's move based on previous player moves. returns CPU move: string"""
    #if player has a favorite, pick its weakness, else pick a random one
    v = list(pastMoves.values())
    weakness = {'rock': 'paper', 'paper': 'scissors', 'scissors': 'rock'}
    if v.count(max(v)) > 1 or sum(v) < 3: #more than one maximum -> no favorite, OR sample too small
        return random.choice(choices)
    else:
        for key in pastMoves:
            if pastMoves[key] == max(v): #find key corresponding to unique max value (favorite) and return its weakness
                return weakness[key]

def detResult(player, CPU, scores):
    """detResult(player, CPU) - determine winner and update scores. return result: string."""
    strength = {'rock': 'scissors', 'paper': 'rock', 'scissors': 'paper'}
    if player == CPU:
        return 'Tie.'
    elif strength[player] == CPU:
        scores['player'] += 1
        return 'You win!'
    else:
        scores['CPU'] += 1
        return 'You Lose.'

def mainGame():
    """mainGame() - type rock, paper, or scissors to play the CPU. type quit to stop playing."""
    playing = True
    scores = {'player': 0, 'CPU': 0}
    pastMoves = {'rock': 0, 'paper': 0, 'scissors': 0}
    choices = 'rock', 'paper', 'scissors'
    while(playing):
        #receive input from player
        playerMove = ''
        while(playerMove not in choices): #repeat until valid input
            playerMove = input('Rock, paper, scissors:\n').lower()
            if playerMove == 'quit':
                playing = False
                break

        if playing:
            CPUMove = CPUPlay(choices, pastMoves)
            print('CPU chooses ' + CPUMove + '!', detResult(playerMove, CPUMove, scores), 'CPU: ' + str(scores['CPU']) + ' You: ' + str(scores['player']), sep='\n', end='\n\n')
            #record player's move for future decisions
            pastMoves[playerMove] += 1

mainGame()