1時間で解けなかったらプログラマ失格問題5をPythonで ref: http://qiita.com/tAkihiko/items/07ede10063ef1c5d7415

a5.py

import itertools as it

nums = [1, 2, 3, 4, 5, 6, 7, 8, 9]
num_str = map(str, nums)
#ops = ["+", "-", "/", "*", ""]
ops = [" + ", " - ", ""]

opss = it.tee(ops, len(nums) - 1)

for op_c in it.product(*opss):
    evl = num_str[0]
    for idx, op in enumerate(op_c):
        evl += op + num_str[idx+1]
    rst = eval(evl)
    if rst == 100:
        print evl