sum to 100

sum100.py

#!/usr/local/bin/python3

from itertools import chain, product
flatten = chain.from_iterable

digits = [ str(x+1) for x in range(9) ]
P, M, C = [ ' + ', ' - ', '']

''' operators = add, sub, concat (str, str)
1 + 2 + 3 + ...
1 - 2 - 3 + ...
1 - 23 + 4 + ...
''' 


def foo(digits, ops):
    return ''.join((flatten(zip(digits, ops)) )) + digits[-1]

assert foo(digits[:4], [P,P,P] ) == '1 + 2 + 3 + 4'

#print(list(product('ab', repeat=3)))

for p in product([P,M,C], repeat=8):
    f = foo(digits, p)
    if eval(f) == 100:
        print(f)