RPS.py

def player(prev_play, opponent_history=[], ngram_model={}):
    import random
    from collections import defaultdict

    if prev_play:
        opponent_history.append(prev_play)

    n = 3 
    if len(opponent_history) >= n + 1:
        key = ''.join(opponent_history[-n - 1:-1])
        next_move = opponent_history[-1]
        if key not in ngram_model:
            ngram_model[key] = defaultdict(int)
        ngram_model[key][next_move] += 1

    if len(opponent_history) >= n:
        key = ''.join(opponent_history[-n:])
        if key in ngram_model:
            prediction = max(ngram_model[key], key=ngram_model[key].get)
        else:
            prediction = random.choice(['R', 'P', 'S'])
    else:
        prediction = random.choice(['R', 'P', 'S'])

    counter = {'R': 'P', 'P': 'S', 'S': 'R'}
    return counter[prediction]