24点.py

import re
import itertools

t = input('输入四个数：')
nums = list(map(int, re.split('\s+', t)))
div = lambda x, y : x // y
signs = [int.__add__, int.__sub__, int.__mul__,  div]
signs_txt = {signs[0]: '+', signs[1]: '-', signs[2]: '*', signs[3]: '/'}
signs_to_txt = lambda x: signs_txt[x]

def pick_three(data):
    ret = []
    for a in data:
        for b in data:
            for c in data:
                ret.append([a, b, c])
    return ret

def calc(sign_lst, num_lst):
    for i in sign_lst:
        a = num_lst.pop()
        b = num_lst.pop()
        num_lst.append(i(a, b))
    return num_lst.pop()
    

def pretty(sign_lst, num_lst):
    ret = []
    sign_lst.append('')
    for i in range(len(num_lst)):
        ret.append(str(num_lst[i]))
        if sign_lst[i] in ['*', '/']:
            ret.insert(0, '(')
            ret.append(')')
        ret.append(str(sign_lst[i]))
    return ' '.join(ret)


for i in pick_three(signs):
    for j in itertools.permutations(nums):
        if calc(i, list(j)) == 24:
            a, b = list(map(signs_to_txt, i)), j[::-1]
            print(pretty(a, b))