使用 Python 的算术运算符和指定的数字 2、3、4、5构造一个表达式，使用所有的4个数字和3个运算符各一次，计算得到28，

1
2
3
4
5
6
7
8
9
10
11
import random

num = list(input().split(" "))
notation = ['-', '+', '/', '*', '**','%']
answer = ''
while answer != 28:
    sign = random.sample (notation, 3)
    figure = random.sample(num, 4)
    assembly = figure[0] + sign[0] + figure[1] + sign[1] + figure[2] + sign[2] + figure[3]
    answer = eval (assembly)
print(assembly, "=", eval (assembly))
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
import itertools

def twentyfour(cards):
    '''史上最短计算24点代码'''
    for nums in itertools.permutations(cards): # 四个数
        for ops in itertools.product('+-*/', repeat = 3): # 三个运算符（可重复！）
            # 构造三种中缀表达式 (bsd)
            bds1 = '({0}{4}{1}){5}({2}{6}{3})'.format(*nums, *ops)  # (a+b)*(c-d)
            bds2 = '(({0}{4}{1}){5}{2}){6}{3}'.format(*nums, *ops)  # (a+b)*c-d
            bds3 = '{0}{4}({1}{5}({2}{6}{3}))'.format(*nums, *ops)  #  a/(b-(c/d))
            
            for bds in [bds1, bds2, bds3]: # 遍历
                try:
                    if abs(eval(bds) - 24.0) < 1e-10:   # eval函数
                        return bds
                except ZeroDivisionError: # 零除错误！
                    continue
    
    return 'Not found!'

cards =[[1,1,1,8],
        [1,1,2,6]]
for card in cards:
    print(twentyfour(card))