calc24

gistfile1.py

# coding: utf-8
from __future__ import division
import itertools

exp_list = ['((%d{}%d){}%d){}%d', '(%d{}%d){}(%d{}%d)',
            '(%d{}(%d{}%d)){}%d', '%d{}((%d{}%d){}%d)',
            '%d{}(%d{}(%d{}%d))']

op_list = list(itertools.product('+ - * /'.split(), repeat=3))

def calc(lst):
    for n in itertools.permutations(lst,4):
        for ex,op in itertools.product(exp_list, op_list):
            exp = ex.format(*op) % n
            try:
                if eval(exp)==24:
                    return exp
            except:pass
    return None

if __name__ == '__main__':
    print calc([5,6,7,8]), '= 24'