best_travel.py

def choose_best_sum(t, k, ls):
    """
    John and Mary want to travel between a few towns A, B, C ... Mary has on a
     sheet of paper a list of distances between these towns. ls = [50, 55, 57,
      58, 60]. John is tired of driving and he says to Mary that he doesn't
      want to drive more than t = 174 miles and he will visit only 3 towns.


    Which distances, hence which towns, they will choose so that the sum of the
    distances is the biggest possible

    to please Mary - but less than t - to please John- ?
    Example:

    With list ls and 3 towns to visit they can make a choice
    between:[50,55,57],
    [50,55,58],[50,55,60],[50,57,58],[50,57,60],[50,58,60],[55,57,58],
    [55,57,60],[55,58,60],[57,58,60].

    The sums of distances are then: 162, 163, 165, 165, 167, 168, 170,
     172, 173, 175.

    The biggest possible sum taking a limit of 174 into account is then 173
    and the distances of the 3 corresponding towns is [55, 58, 60].

    The function chooseBestSum (or choose_best_sum or ... depending on the
    language) will take as parameters t (maximum sum of distances, integer >=
    0), k (number of towns to visit, k >= 1) and ls (list of distances, all
    distances are positive or null integers and this list has at least one
    element). The function returns the "best" sum ie the biggest possible sum
    of k distances less than or equal to the given limit t, if that sum
    exists, or otherwise nil, null, None, Nothing, depending on the language.
    With C++, C, Rust, Swift, Go return -1.


    Examples:

    ts = [50, 55, 56, 57, 58] choose_best_sum(163, 3, ts) -> 163

    xs = [50] choose_best_sum(163, 3, xs) -> nil (or null or ... or -1 (C++,
    C, Rust, Swift, Go)

    ys = [91, 74, 73, 85, 73, 81, 87] choose_best_sum(230, 3, ys) -> 228
    """
    from itertools import combinations
    list1 = list(combinations(ls, k))
    list2 = []
    for item in list1:
        list2.append(sum(n for n in item))
    templist = [a for a in list2 if a <= t]
    if templist:
        return max(templist)
    # try:
    #     return max(sum(i) for i in itertools.combinations(ls,k) if
    #     sum(i)<=t)
    # except:
    #     return None