+ 2

Help. Are you capable of solving this program?

Can you write a program to find the number of ordered 64-tuples {a1,a2,...,a64}  such that a1,a2,...,a64 are distinct elements of  {1,2,...,2017} and a1+a2+...+a64 is divisible by 2017? Note: this problem is really hard to solve without computers.

17th May 2018, 6:38 PM
Heisenberg
Heisenberg - avatar
7 Antworten
+ 1
Well that would be difficult, to generate variables, I don't know, if there is a module for it, but I suggest rather to use dictionaries, than you would do that with variables, you would do that by strings as keys of dictionaries, i'll give you a code very soon.
17th May 2018, 6:44 PM
Seb TheS
Seb TheS - avatar
+ 1
I Can offer a simple solution to the problem without a program: {a1=1, a2=2 .. a32=32, a33=1984, a34=1985.. a64=2016} So: a1+a64 = a2+a63 = ... = 2017 The elements are different and sum up to 67424 which is 2017x32 so it's divisible by 2017. Am I missing something? It was too easy... Probably won't be too hard to write a program using that algorithm (in case my answer is right)
17th May 2018, 8:08 PM
Jack
Jack - avatar
+ 1
Jack ,you found one tuple that satisfies the conditions, but the problem is to find how many tuples there are, you better write a program :D
17th May 2018, 9:03 PM
Heisenberg
Heisenberg - avatar
0
Dictionary = {} for i in range(2017): Dictionary["a" + str(i + 1)] = i print(Dictionary)
17th May 2018, 6:48 PM
Seb TheS
Seb TheS - avatar
0
I can't run it here either, but, where does it take in to account the part "a1+a2+... +a64 is divisible by 2017"?
17th May 2018, 6:52 PM
Heisenberg
Heisenberg - avatar
0
#Defines some functions. def AB(C, D): if sum(C) != 0: if D % sum(C) == 0: print(sum(C)) #Takes a value, which will be divided by numbers from 0 to 63. Value = 2017 Range = list(range(64)) #Indexes Range by 64! different ways! A = 0 B = 0 while True: while True: AB(Range[A:B], Value) B += 1 if B >= 63: B = 0 break A += 1 if A >= 63: break
17th May 2018, 8:59 PM
Seb TheS
Seb TheS - avatar
0
Heisenberg Yeah, it's really a hard problem. I got a headache while thinking of a solution which won't go through the 9x10^121 options of choosing a subset of 64 elements out of 2017 elements.
18th May 2018, 6:28 AM
Jack
Jack - avatar