Coding Challenge - Morris Sequence
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Well, he did only ask about the length of the 100 th number. So according to Look-and-say sequence - Wikipedia[^]. Dave told us that the 50th number had length:
L50 = 894810
And the wikipedia article said:
L_n+1/L_n= lambda = 1.303577269034
so....
L50*lambda^(50)= 511175198256
if my math is right enough. Very hard programming challange :D
Exact length is required and that's not the answer.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave Kreskowiak -
PS. Do you want the text file? ... ... ... :laugh: :laugh: :laugh:
Good luck posting it! :laugh:
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave Kreskowiak -
Oh, it's possible. My machine is sitting here listing the iteration, length, and time to calculate for each of the 100 numbers.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave KreskowiakGood to know! Currently at line 82 and the file size for line 82 alone is over 4 Gigabytes.
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
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Good to know! Currently at line 82 and the file size for line 82 alone is over 4 Gigabytes.
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
4,326,816,254 to be exact.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave Kreskowiak -
Exact length is required and that's not the answer.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave KreskowiakCant be far off :)
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Cant be far off :)
:-D
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave Kreskowiak -
I have already text files over 2.2 GB so I think you'll have to delete them as you gom at least that's what I do. And I think using bytes is cheating :laugh: also I didn't know that 3 would be the highest number. I don't think is enough not if you start at 3,4,5 or any other number, at least I got some 5 then. Or my code was wrong.
Kenneth Haugland wrote:
I don't think is enough not if you start at 3,4,5 or any other number, at least I got some 5 then.
Whatever digit you start with will always be in the last position. No other digit will exceed 3, no matter how many iterations you try. For example, if in iteration
nyou get41, then that means iterationn-1must have had...x1111.... But given the rules of the sequence, that would have to be written as either(x+1)1or21.
"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer
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Kenneth Haugland wrote:
I don't think is enough not if you start at 3,4,5 or any other number, at least I got some 5 then.
Whatever digit you start with will always be in the last position. No other digit will exceed 3, no matter how many iterations you try. For example, if in iteration
nyou get41, then that means iterationn-1must have had...x1111.... But given the rules of the sequence, that would have to be written as either(x+1)1or21.
"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer
Ah, yes that makes sense. Also seems to be that the higher the number of iterations the higher of LSB seems to be equal? if you can find that formula you might shorten the calculations by quite a bit.
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Oh, it's possible. My machine is sitting here listing the iteration, length, and time to calculate for each of the 100 numbers.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave KreskowiakSo how long did it take? Did you do something in parallell or?
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So how long did it take? Did you do something in parallell or?
I'll say 82 took my machine 59 seconds.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave Kreskowiak -
It's also known as the Conway Sequence, Look and Say Sequence, and probably some others. It's rather simple. Start with a 1 and then describe what you see for the next iteration. So, starting at 1, the next number is one 1 (11), the next is two 1 (21), then one 2 one 1 (1211), and so on:
1
11
21
1211
111221
312211The question to answer is what's the length in digits of the 100th number in the chain, starting with "1" as the first? The first six numbers have been given above. You could write it out by hand, but I wouldn't recommend it, and as developers, that's not what we do. The seemingly simple challenge is to write the code to come up with the answer. The only hint you get is the 50th number is 894,810 digits long. Oh, and don't bother Googling for code. Those examples will only get you so far and definitely won't get you to the answer.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave Kreskowiak -
85 MINUTES?! You'll be running this for about a week to get to 100. It can be done a lot quicker than that. The 76th number took 12 seconds on my machine and it's a "nothing special" machine.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave Kreskowiak -
85 MINUTES?! You'll be running this for about a week to get to 100. It can be done a lot quicker than that. The 76th number took 12 seconds on my machine and it's a "nothing special" machine.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave Kreskowiak -
It's also known as the Conway Sequence, Look and Say Sequence, and probably some others. It's rather simple. Start with a 1 and then describe what you see for the next iteration. So, starting at 1, the next number is one 1 (11), the next is two 1 (21), then one 2 one 1 (1211), and so on:
1
11
21
1211
111221
312211The question to answer is what's the length in digits of the 100th number in the chain, starting with "1" as the first? The first six numbers have been given above. You could write it out by hand, but I wouldn't recommend it, and as developers, that's not what we do. The seemingly simple challenge is to write the code to come up with the answer. The only hint you get is the 50th number is 894,810 digits long. Oh, and don't bother Googling for code. Those examples will only get you so far and definitely won't get you to the answer.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave Kreskowiak- Strings and string methods are not going to do it. They're too slow and take up too much memory. 2) The only digits you see in any of these numbers are 1, 2, and 3. It seems like a waste to use an entire byte to store each digit. 3) If you graph the math on the progression of the length of these numbers, you'll see that on a LOGARITHMIC SCALE, the graph is about a 40 degree line. What would that look like on a normal X/Y scale? 4) You cannot do this "in memory", without going to the extremes of cleverness, and even then, you'd still need a gargantuan amount of RAM.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave Kreskowiak -
4,326,816,254 to be exact.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave KreskowiakYep - that's the count I get too :thumbsup:
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
-
- Strings and string methods are not going to do it. They're too slow and take up too much memory. 2) The only digits you see in any of these numbers are 1, 2, and 3. It seems like a waste to use an entire byte to store each digit. 3) If you graph the math on the progression of the length of these numbers, you'll see that on a LOGARITHMIC SCALE, the graph is about a 40 degree line. What would that look like on a normal X/Y scale? 4) You cannot do this "in memory", without going to the extremes of cleverness, and even then, you'd still need a gargantuan amount of RAM.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave Kreskowiak -
Well, he did only ask about the length of the 100 th number. So according to Look-and-say sequence - Wikipedia[^]. Dave told us that the 50th number had length:
L50 = 894810
And the wikipedia article said:
L_n+1/L_n= lambda = 1.303577269034
so....
L50*lambda^(50)= 511175198256
if my math is right enough. Very hard programming challange :D
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- Strings and string methods are not going to do it. They're too slow and take up too much memory. 2) The only digits you see in any of these numbers are 1, 2, and 3. It seems like a waste to use an entire byte to store each digit. 3) If you graph the math on the progression of the length of these numbers, you'll see that on a LOGARITHMIC SCALE, the graph is about a 40 degree line. What would that look like on a normal X/Y scale? 4) You cannot do this "in memory", without going to the extremes of cleverness, and even then, you'd still need a gargantuan amount of RAM.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave KreskowiakThe length of row n won't exceed twice the length of row n-1 , yes? The result is computable, therefore a Turing Machine can compute it, and, because Turing Machines have virtually unlimited storage, simply use one.
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The length of row n won't exceed twice the length of row n-1 , yes? The result is computable, therefore a Turing Machine can compute it, and, because Turing Machines have virtually unlimited storage, simply use one.
You build the machine and I'll go make the infinite paper tape.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave Kreskowiak -
It's also known as the Conway Sequence, Look and Say Sequence, and probably some others. It's rather simple. Start with a 1 and then describe what you see for the next iteration. So, starting at 1, the next number is one 1 (11), the next is two 1 (21), then one 2 one 1 (1211), and so on:
1
11
21
1211
111221
312211The question to answer is what's the length in digits of the 100th number in the chain, starting with "1" as the first? The first six numbers have been given above. You could write it out by hand, but I wouldn't recommend it, and as developers, that's not what we do. The seemingly simple challenge is to write the code to come up with the answer. The only hint you get is the 50th number is 894,810 digits long. Oh, and don't bother Googling for code. Those examples will only get you so far and definitely won't get you to the answer.
System.ItDidntWorkException: Something didn't work as expected. C# - How to debug code[^]. Seriously, go read these articles.
Dave KreskowiakThe spec isn't clear! Send it back! :wtf: As this is, in essence, a compression algorithm, at line 8->9 (according to the OEIS) I would do:
1113213211
11 132132 11 <== three subsequences
21 2132 21 <== three outputs, eight digits
Which is shorter than their naive result of:
1113213211
111 3 2 1 3 2 11 <== seven subsequences
31 13 12 11 13 12 21 <== seven outputs, fourteen digits
A 40% saving. The complexity of the algorithm increases due to seeking how to split the input into the fewest subsequences of some repetition length (1 in the naive implementation).
