Videonauth's Help Box

Videonauth

1:22 AM

@edwinksl you're here ?

edwinksl

1:43 AM

just back from outside

what's up

Videonauth

well I actually recode a few things to keep stuff fresh in my head and just did the collatz function,

my result is this:

def collatz(value):
    counter = 0
    while value != 1:
        if value % 2 == 0:
            value /= 2
        else:
            value = value * 3 + 1
        counter += 1
        print("Step: " + str(counter) + " Value: " + str(value))
    print("After " + str(counter) + "steps value is 1")

whell the if part i would write in c++ ilke this:

edwinksl

that looks ok

Videonauth

value = value % 2 == 0 ? value / 2 : value * 3 + 1;

edwinksl

did you eventually reach 1

Videonauth

is there something like that in python?

i did

edwinksl

1:47 AM

here stackoverflow.com/questions/394809/…

Videonauth

so it would be:

value = value / 2 if value % 2 == 0 else value * 3 + 1

?

yes seems so

just tested it

edwinksl

yup that's correct

Videonauth

/usr/bin/python3.5 /home/michael/python/learning/collatz.py 50
Step: 1 Value: 25.0
Step: 2 Value: 76.0
Step: 3 Value: 38.0
Step: 4 Value: 19.0
Step: 5 Value: 58.0
Step: 6 Value: 29.0
Step: 7 Value: 88.0
Step: 8 Value: 44.0
Step: 9 Value: 22.0
Step: 10 Value: 11.0
Step: 11 Value: 34.0
Step: 12 Value: 17.0
Step: 13 Value: 52.0
Step: 14 Value: 26.0
Step: 15 Value: 13.0
Step: 16 Value: 40.0
Step: 17 Value: 20.0
Step: 18 Value: 10.0
Step: 19 Value: 5.0
Step: 20 Value: 16.0
Step: 21 Value: 8.0
Step: 22 Value: 4.0

edwinksl

some people don't like it because the order seems unintuitive

Videonauth

yeah kinda, the c++ one makes more sense

edwinksl

1:52 AM

to each his/her own

some will prefer the if else

eg thomas w prefers explicit if else

Videonauth

well depends sometimes its easier to write a ternary operator for readability

well now lets see if i can remember the greatest common divisor solutions

Videonauth

2:22 AM

def gcd_bruteforce(value_one, value_two):
    if value_one > value_two:
        divisor = value_two
    else:
        divisor = value_one
    while value_one % divisor != 0 or value_two % divisor != 0:
        divisor -= 1
    print("The gratest common divisor of " + str(value_one) + " and " + str(value_two) + " is " + str(divisor))

now only two left euklid version and the quick euklid version

edwinksl

you could use python to finish project euler ;D

Videonauth

:p

well like i said this is only to keep stuff memorized

after that bubble sort and tree sort

edwinksl

projecteuler.net/problem=14

Videonauth

:)

edwinksl

only requires slightly modification of what you had

probably should use memoization to speed it up

Videonauth

2:29 AM

yeah sure needs a store of all results

edwinksl

if not, i think it runs in decent time, no big deal

Videonauth

and this would be a big big database at the end

and to prove euler right would mean to cover the whole number room we deem worthy as solution and that would be more than one googol

imagine theres even a boinc project for that

and they are not done yet and it runs since years already

Collatz conjecture

The Collatz conjecture is a conjecture in mathematics named after Lothar Collatz, who first proposed it in 1937. The conjecture is also known as the 3n + 1 conjecture, the Ulam conjecture (after Stanisław Ulam), Kakutani's problem (after Shizuo Kakutani), the Thwaites conjecture (after Sir Bryan Thwaites), Hasse's algorithm (after Helmut Hasse), or the Syracuse problem; the sequence of numbers involved is referred to as the hailstone sequence or hailstone numbers (because the values are usually subject to multiple descents and ascents like hailstones in a cloud), or as wondrous numbers. The...

Videonauth

3:02 AM

if you're succeeding to prove collatz right, youre a rich man :) 5 million dollars richer than before

its one of the millennium problems

edwinksl

not worth it :D

unfortunately mathematics is not a field where novices can actually luck out and beat the experts

it simply doesn't happen

Videonauth

yep

but i love maths tho

still i not studied it

Videonauth

3:30 AM

but my solution for this problem nr 14 on euler.net i got this:

def collatz(value):
    start = value
    counter = 0
    while value != 1:
        if value % 2 == 0:
            value /= 2
        else:
            value = value * 3 + 1
        counter += 1
    return [start, counter]

if __name__ == "__main__":
    max_steps = [0, 0]
    for number in range(1, 1000000):
        result = collatz(number)
        if result[1] > max_steps[1]:
            max_steps = result
    print("The number below 1,000,000 which took the most steps to calculate is:")
    print(str(max_steps[0]) + " with " + str(max_steps[1]) + "steps.")

999994 : 113
999995 : 258
999996 : 113
999997 : 113
999998 : 258
999999 : 258
The number below 1,000,000 which took the most steps to calculate is:
837799 with 524steps.

edwinksl

3:53 AM

is that the correct answer?

Videonauth

well according to my script yes

edwinksl

what does project euler say :P

Videonauth

dunno im not registred there

and i cant find anything wrong in my script

it iterates over all numbers from 1 to 999999 and only if it finds a result with a higher step count it gets saved

@edwinksl what does project euler say? xD