import random

def draw_card(draw_count, gold_probability):
    if draw_count >= 7:
        return "金"
    else:
        card = random.choices(["紫", "金"], [gold_probability, 1 - gold_probability])[0]
        return card

def play_game():
    draw_count = 0
    gold_probability = 0.05
    while True:
        user_input = input("你想抽卡吗？输入'y'或'n': ")
        if user_input == 'y':
            card = draw_card(draw_count, gold_probability)
            print("你抽到了一张", card)
            draw_count += 1
            gold_probability = 0.5 if draw_count >= 3 else gold_probability
        elif user_input == 'n':
            print("好的，游戏结束。")
            break
        else:
            print("无效的输入，请重新输入。")

play_game()