working on codeeval challenge - https://www.codeeval.com/open_challenges/190/

where_is_the_tea.py

import itertools
import operator

# have the allowed operators in an array
def get_operator_fn(op):
    return {
        '+' : operator.add,
        '-' : operator.sub,
        '*' : operator.mul,
        }[op]

# do the math operation from operator as string
def eval_binary_expr(op1, operator, op2):
    op1,op2 = int(op1), int(op2)
    return get_operator_fn(operator)(op1, op2)

# get string input as integer iteratables
# TODO replace this later as IO from file and all of that

input_string = "44 6 1 49 47"
input_array = input_string.split()

# have operators as iteratable
operands_string = "* + -"
operands_array = operands_string.split()

my_flag = False


# for all permutations of numbers drawn, do a dirty brute force check
for number_subset in itertools.permutations(input_array, 5):
  # TODO replace this later with something that is not dirty

  for op1 in operands_array:
    val1 = eval_binary_expr(number_subset[0], op1, number_subset[1])

    for op2 in operands_array:
      val2 = eval_binary_expr(val1, op2, number_subset[2])

      for op3 in operands_array:
        val3 = eval_binary_expr(val2, op3, number_subset[3])

        for op4 in operands_array:
          val4 = eval_binary_expr(val3, op4, number_subset[4])

          if (val4 == 42):
            my_flag = True
              

print "Yes" if (my_flag == True) else "No"

where_is_the_tea_v2.py

from itertools import permutations
from itertools import combinations_with_replacement as cartesian_product
import sys

# read in the supplied input file
lines = open(sys.argv[1], 'r')

# have the allowed operators in an array
signs = ['+', '-', '*']

# put together the expression to be evaluated at once
# using a given permutation of numbers drawn and math signs
def make_test_str(perm, sp):
    test_str = ""
    for i in xrange(0, 5):
        test_str += perm[i]
        if i < 4:
            test_str += sp[i]
    return test_str

# print if there is a possible 42 solution for a given number set
def has_solution(num_set):

    # get all permutations of the set
    perm_set = permutations(num_set, 5)

    # for each permutation try all math sign combinations
    for p in perm_set:
        sp = cartesian_product(signs, 4)
        for s in sp:
            test_str = make_test_str(p, s)
            print "test_str is", test_str
            result = eval(test_str)

            if result is 42:
                return 'YES'

    return 'NO'
            


# get each line from supplied input file
for line in lines:
    num_set = line.replace("\n", "").split(" ")
    print has_solution(num_set)

lines.close()