Problem 079

A place to air possible concerns or difficulties in understanding ProjectEuler problems. This forum is not meant to publish solutions. This forum is NOT meant to discuss solution methods or giving hints how a problem can be solved.
Forum rules
As your posts will be visible to the general public you are requested to be thoughtful in not posting anything that might explicitly give away how to solve a particular problem.

This forum is NOT meant to discuss solution methods for a problem.

In particular don't post any code fragments or results.

Don't start begging others to give partial answers to problems

Don't ask for hints how to solve a problem

Don't start a new topic for a problem if there already exists one


See also the topics:
Don't post any spoilers
Comments, questions and clarifications about PE problems.
Post Reply
3n1gm4
Posts: 34
Joined: Sun Jul 20, 2008 1:46 pm

Problem 079

Post by 3n1gm4 »

Can a char be repeated in the passkey?
i.e. 51515151?!? (it is just an example)
Ikcelaks
Posts: 28
Joined: Wed Oct 15, 2008 9:08 pm

Re: Problem #79

Post by Ikcelaks »

The problem text doesn't disallow it.
3n1gm4
Posts: 34
Joined: Sun Jul 20, 2008 1:46 pm

Re: Problem #79

Post by 3n1gm4 »

Thank you anyway ( :P ), solved :D
ZePedroPONTO
Posts: 1
Joined: Fri Apr 16, 2010 3:33 pm

Problem 079 - just nitpicking

Post by ZePedroPONTO »

Hi, this is my first post, I've been enjoying the website a lot.

My issue is very little, really. Problem 79 reads "they may asked for the 2nd, 3rd, and 5th characters"
Isn't the word "be" missing there? "they may be asked"

That's it. Thank you, everybody. :)
harryh
Posts: 2091
Joined: Tue Aug 22, 2006 9:33 pm
Location: Thessaloniki, Greece

Re: Problem 079

Post by harryh »

Good spot; changed it to "they may ask for the 2nd, 3rd ..." (meaning that the security system(s) may ask...)

Before starting a new topic, please make sure that the topic of a particular problem does not already exist (otehrwise this forum becomes extremely mess...)
jozefovovic
Posts: 2
Joined: Fri Jan 27, 2012 11:40 am

Re: Problem 079

Post by jozefovovic »

Hi everybody,

I'm a little bit confused with this problem. I have to find the smalles count of digits number, for which are numbers in keylog.txt possible solutions. And numbers in keylog.txt have form XYZ where, Y is between X and Z in for me unknown number?
thundre
Posts: 356
Joined: Sun Mar 27, 2011 10:01 am

Re: Problem 079

Post by thundre »

jozefovovic wrote:I'm a little bit confused with this problem. I have to find the smalles count of digits number, for which are numbers in keylog.txt possible solutions. And numbers in keylog.txt have form XYZ where, Y is between X and Z in for me unknown number?
Yes, that's it. The answer contains X,Y,Z in that order, usually with other numbers in between.
Image
satyres
Posts: 31
Joined: Thu Feb 20, 2014 2:48 pm

Re: Problem 079

Post by satyres »

Hi, this my first post on this forum !
I want to thanks all who have created this website just awesome !
i have a little missunderstood for this porblem , because english is not my mother tongue !
What do we mean by the "the shortest possible secret " do we mean the length of the passcode???
The file KeyLogs containt always the 2nd, 3rd, and 5th characters??
[If any one can explain what am i supposed to do it will be excellent]
I'm sorry for my questions may be stupid ! but i'm really confused !
Thanks so much !
User avatar
Marcus_Andrews
Administrator
Posts: 1637
Joined: Wed Nov 09, 2011 5:23 pm

Re: Problem 079

Post by Marcus_Andrews »

satyres wrote:Hi, this my first post on this forum !
I want to thanks all who have created this website just awesome !
i have a little missunderstood for this porblem , because english is not my mother tongue !
What do we mean by the "the shortest possible secret " do we mean the length of the passcode???
The file KeyLogs containt always the 2nd, 3rd, and 5th characters??
[If any one can explain what am i supposed to do it will be excellent]
I'm sorry for my questions may be stupid ! but i'm really confused !
Thanks so much !
"2nd, 3rd, and 5th characters" = this was just an example.

For example, if the passcode were 846295784, and I asked you for three random numbers, I might ask "What is the first, third, and sixth number?" You would answer with the login "865."

keylog.txt contains many successful logins for the same passcode (three random numbers from the passcode, in order). So if you have some valid login xyz, then x comes before y which comes before z in the passcode. The question is asking for the shortest possible passcode that satisfies all the login attempts in keylog.txt.

Let me know if you have any more questions!
satyres
Posts: 31
Joined: Thu Feb 20, 2014 2:48 pm

Re: Problem 079

Post by satyres »

Marcus Stuhr wrote:
satyres wrote:Hi, this my first post on this forum !
I want to thanks all who have created this website just awesome !
i have a little missunderstood for this porblem , because english is not my mother tongue !
What do we mean by the "the shortest possible secret " do we mean the length of the passcode???
The file KeyLogs containt always the 2nd, 3rd, and 5th characters??
[If any one can explain what am i supposed to do it will be excellent]
I'm sorry for my questions may be stupid ! but i'm really confused !
Thanks so much !
"2nd, 3rd, and 5th characters" = this was just an example.

For example, if the passcode were 846295784, and I asked you for three random numbers, I might ask "What is the first, third, and sixth number?" You would answer with the login "865."

keylog.txt contains many successful logins for the same passcode (three random numbers from the passcode, in order). So if you have some valid login xyz, then x comes before y which comes before z in the passcode. The question is asking for the shortest possible passcode that satisfies all the login attempts in keylog.txt.

Let me know if you have any more questions!
Thanks so much for you help ! i solved the problem :) !
ianchristy
Posts: 1
Joined: Wed Oct 14, 2020 1:11 am

Problem 79

Post by ianchristy »

There is nothing in problem 79 that states you MUST have digits either between the passcode digits, not before, nor after. the example is just an example. "the three characters are always asked for in order," there are a max of n digits in the data file provided, so the answer is simply n, the length of the longest valid password.
If the problem statement "The bank WILL prompt you with an arbitrary string of digits that include the digits of your passcode" then the problem statement is clear. As it stands now you might ASSUME that will happen, but you should not be making any assumptions. Problem 79 (View Problem)
Post Reply