题解 | #24点运算#

def calculate(cards, target):
    # print(cards, target)
    global op_list
    if len(cards) == 1:
        if cards[0] == target:
            return cards
        else:
            return False
    for i in cards:
        # print("current i:", i)
        remaining_cards = cards.copy()
        remaining_cards.remove(i)
        # +:
        ans = calculate(remaining_cards, target - i)
        if ans is not False:
            ans.append(i)
            op_list.append("+")
            return ans
        # -:
        ans = calculate(remaining_cards, target + i)
        if ans is not False:
            ans.append(i)
            op_list.append("-")
            return ans
        # /:
        ans = calculate(remaining_cards, target * i)
        if ans is not False:
            ans.append(i)
            op_list.append("/")
            return ans
        # *:
        if target % i == 0:
            ans = calculate(remaining_cards, target // i)
            if ans is not False:
                ans.append(i)
                op_list.append("*")
                return ans
    return False  # 表示算不出来


while True:
    try:
        l = input().split()
        if "joker" in l or "JOKER" in l:
            print("ERROR")
        cards = []
        dic = {"J": 11, "Q":12, 'K':13, "A":1}
        for i in l:
            if i in dic:
                cards.append(dic[i])
            else:
                cards.append(int(i))
        # print(cards)
        # 把一个数字放到最后，看前三个数字的结果加减乘除能不能得到24.
        op_list = []
        ans = calculate(cards, 24)
        if ans is False:
            print("NONE")
        else:
            res = ""
            for i in range(3):
                if ans[i] == 11:
                    res += "J" + op_list[i]
                elif ans[i] == 12:
                    res += "Q" + op_list[i]
                elif ans[i] == 13:
                    res += "K" + op_list[i]
                elif ans[i] == 1:
                    res += "A" + op_list[i]
                else:
                    res += str(ans[i]) + op_list[i]
            if ans[3] == 11:
                res += "J" + op_list[i]
            elif ans[3] == 12:
                res += "Q" + op_list[i]
            elif ans[3] == 13:
                res += "K" + op_list[i]
            elif ans[3] == 1:
                res += "A" + op_list[i]
            else:
                res += str(ans[3])
            print(res)
    except:
        break