kandi X-RAY | Answer Summary
kandi X-RAY | Answer Summary
移动端的考试系统源码,实现做题,查看解析,提交答案的流程操作,采用任务栈的形式显现做题原理。android考试系统源码,模拟考试答题 欢迎star, 本系统目前版本是离线版本,模拟做题都是通过写死的,在后期的维护中将通过搭建后台服务器,显现动态做题,以及不同学科的做题,当然,也是开源的,喜欢的小伙伴也可以继续关注,有你想不到的以为哦
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Top functions reviewed by kandi - BETA
- On create
- Upload examination
- Display time out dialog
- Load data
- Destroy the timer
- Stop the timer
- Called when the window is created
- Initialize view
- This method is used to instantiate a view
- Insert error question
- Gets a view at a specific position
- Handle keyboard down
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- Initializes the overview
- Stop the handler
- On resume
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Answer Key Features
Answer Examples and Code Snippets
def solution() -> int:
"""
To evaluate the sum, Used decimal python module to calculate the decimal
places up to 100, the most important thing would be take calculate
a few extra places for decimal otherwise there will be rounding
def solution(limit: int = 1000000) -> int:
"""
Return the number of different square laminae that can be formed using up to
one million tiles.
>>> solution(100)
41
"""
answer = 0
for outer_width in range(3
def solution(n: int = 1000) -> int:
"""Returns the index of the first term in the Fibonacci sequence to contain
n digits.
>>> solution(1000)
4782
>>> solution(100)
476
>>> solution(50)
23
Community Discussions
Trending Discussions on Answer
QUESTION
I've created a new Java project in IntelliJ with Gradle that uses Java 17. When running my app it has the error Cause: error: invalid source release: 17
.
My Settings
I've installed openjdk-17
through IntelliJ
and set it as my Project SDK
.
The Project language level
has been set to 17 - Sealed types, always-strict floating-point semantics
.
In Modules -> Sources
I've set the Language level
to Project default (17 - Sealed types, always strict floating-point semantics)
.
In Modules -> Dependencies
I've set the Module SDK
to Project SDK openjdk-17
.
In Settings -> Build, Execution, Deployment -> Compiler -> Java Compiler
I've set the Project bytecode version
to 17
.
Gradle
...ANSWER
Answered 2021-Oct-24 at 14:23The message typically entails that your JAVA_HOME environment variable points to a different Java version.
Here are the steps to follow:
- Close IntelliJ IDEA
- Open a terminal window and check your JAVA_HOME variable value:
- *nix system:
echo $JAVA_HOME
- Windows system:
echo %JAVA_HOME%
- *nix system:
- The JAVA_HOME path should be pointing to a different path, then set it to the openjdk-17 path:
- *nix system:
export JAVA_HOME=/path/to/openjdk-17
- Windows system:
set JAVA_HOME=path\to\openjdk-17
- *nix system:
- Open your project again in IntelliJ IDEA
- Make sure to set both source and target compatibility versions (not only the
sourceCompatibility
)
You should be able to build your project.
EDIT: Gradle ToolchainYou may need also to instruct Gradle to use a different JVM than the one it uses itself by setting the Java plugin toolchain to your target version:
QUESTION
I need to calculate the square root of some numbers, for example √9 = 3
and √2 = 1.4142
. How can I do it in Python?
The inputs will probably be all positive integers, and relatively small (say less than a billion), but just in case they're not, is there anything that might break?
Related
- Integer square root in python
- Is there a short-hand for nth root of x in Python?
- Difference between **(1/2), math.sqrt and cmath.sqrt?
- Why is math.sqrt() incorrect for large numbers?
- Python sqrt limit for very large numbers?
- Which is faster in Python: x**.5 or math.sqrt(x)?
- Why does Python give the "wrong" answer for square root? (specific to Python 2)
- calculating n-th roots using Python 3's decimal module
- How can I take the square root of -1 using python? (focused on NumPy)
- Arbitrary precision of square roots
Note: This is an attempt at a canonical question after a discussion on Meta about an existing question with the same title.
...ANSWER
Answered 2022-Feb-04 at 19:44math.sqrt()
The math
module from the standard library has a sqrt
function to calculate the square root of a number. It takes any type that can be converted to float
(which includes int
) as an argument and returns a float
.
QUESTION
So, I'm using Flutter and on running the App, I receive errors like these in the debug console:
...ANSWER
Answered 2021-Jul-31 at 19:43It not happen becuase of you have two build-tools version installed. It happens because of caches so on android studio just invalidating caches and restarting will fix this.
QUESTION
I have read several answers on SO already, and gathered these use-cases:
- When a function
panic!
s - When a function has an infinite loop in it
But it is still unclear to me why we need to define the function like this:
...ANSWER
Answered 2022-Jan-22 at 13:23The main difference between these signatures boils down to the fact that !
can coerce into any other type, and thus is compatible with any other type (since this code path is never taken, we can assume it to be of any type we need). It's important when we have multiple possible code paths, such as if-else
or match
.
For example, consider the following (probably contrived, but hopefully clear enough) code:
QUESTION
I've downloaded Android Studio from the official website, the one for M1 chip (arm).
Basically running it for the first time, the error is the following:
...ANSWER
Answered 2021-Nov-07 at 09:40This is what solved it for me on my M1.
- Go to Android Studio Preview and download the latest Canary build for Apple chip (Chipmunk). Don't worry this is just to get through the initial setup.
- Unpack it, run it, let it install all the SDK components, accept licenses, etc as usual.
- Once it's done, simply close it and delete it.
Now when you start your stable Android Studio (Arctic Fox) you should not see the error.
QUESTION
After Android Studio upgraded itself to version Arctic Fox, I now get these strange sub-windows in my code editor that I can't get rid of. If I click in either of the 2 sub-windows (a one-line window at the top or a 5-line window underneath it (see pic below), it scrolls to the code in question and the sub-windows disappear. But as soon as I navigate away from that code, these sub-windows mysteriously reappear. I can't figure out how to get rid of this.
I restarted Studio and it seemed to go away. Then I refactored a piece of code (Extract to Method Ctrl+Alt+M) and then these windows appeared again. Sometimes these windows appear on a 2nd monitor instead of on top of the code area on the monitor with Android Studio. But eventually they end up back on top of my code editor window.
I have searched hi and low for what this is. Studio help, new features, blog, etc. I am sure that I am just using the wrong terminology to find the answer, so hoping someone else knows.
...ANSWER
Answered 2021-Aug-15 at 15:29Just stumbled upon the same thing (strange windows upon attempting to refactor some code after updating to Arctic Fox). After a lot of searching around the options/menus/internet this fixed it for me:
Navigate to:
File > Settings... > Editor > Code Editing
under
Refactorings > Specify refactoring options:
select
In modal dialogs
Press OK.
Fingers crossed refactoring works.
🤞
Further step: Restart Android Studio
QUESTION
How do I get details of a veracode vulnerability report?
I'm a maintainer of a popular JS library, Ramda, and we've recently received a report that the library is subject to a prototype pollution vulnerability. This has been tracked back to a veracode report that says:
ramda is vulnerable to prototype pollution. An attacker can inject properties into existing construct prototypes via the
_curry2
function and modify attributes such as__proto__
,constructor
, andprototype
.
I understand what they're talking about for Prototype Pollution. A good explanation is at snyk's writeup for lodash.merge
. Ramda's design is different, and the obvious analogous Ramda code is not subject to this sort of vulnerability. That does not mean that no part of Ramda is subject to it. But the report contains no details, no code snippet, and no means to challenge their findings.
The details of their description are clearly wrong. _curry2
could not possibly be subject to this problem. But as that function is used as a wrapper to many other functions, it's possible that there is a real vulnerability hidden by the reporter's misunderstanding.
Is there a way to get details of this error report? A snippet of code that demonstrates the problem? Anything? I have filled out their contact form. An answer may still be coming, as it was only 24 hours ago, but I'm not holding my breath -- it seems to be mostly a sales form. All the searching I've done leads to information about how to use their security tool and pretty much nothing about how their custom reports are created. And I can't find this in CVE databases.
...ANSWER
Answered 2022-Jan-07 at 21:46Ok, so to answer my own question, here's how to get the details on a Veracode vulnerability report in less than four weeks and in only fifty-five easy steps.
Pre-workHave someone post an issue against your library suggesting that its
mapObjIndexed
function is subject to the prototype pollution vulnerability.Respond to say that you don't think the user has demonstrated that well-known vulnerability, but that you will dig deeper.
Write a detailed post described what that vulnerability means and demonstrate that the library is not in fact subject to it, or or at least that the example supplied does not demonstrate it.
Carry on a short conversation with interested parties explaining the point more thoroughly and responding to objections.
Leave the issue open for a while so the original reporter can argue the point and respond. 1
Receive a comment on the issue that says that the user has received
a VULN ticket to fix this
Prototype Pollution vulnerability found in ramda.
Carry on a discussion regarding this comment to learn that there is a report that claims that
ramda is vulnerable to prototype pollution. An attacker can inject properties into existing construct prototypes via the
_curry2
function and modify attributes such as__proto__
,constructor
, andprototype
.and eventually learn that this is due to a report from the software security company Veracode.
Examine that report to find that it has no details, no explanation of how to trigger the vulnerability, and no suggested fix.
Examine the report and other parts of the Veracode site to find there is no public mechanism to challenge such a report.
Report back to the library's issue that the report must be wrong, as the function mentioned could not possibly generate the behavior described.
Post an actual example of the vulnerability under discussion and a parallel snippet from the library to demonstrate that it doesn't share the problem.
Find Veracode's online support form, and submit a request for help. Keep your expectations low, as this is probably for the sales department.
Post a StackOverflow Question2 asking how to find details of a Veracode vulnerability report, using enough details that if the community has the knowledge, it should be easy to answer.
- Try to enjoy your Friday and Saturday. Don't obsessively check your email to see if Veracode has responded. Don't visit the StackOverflow question every hour to see if anyone has posted a solution. Really, don't do these things; they don't help.
- Add a 250-reputation point bounty to the StackOverflow question, trying to get additional attention from the smart people who must have dealt with this before.
- Find direct email support addresses on the Veracode site, and send an email asking for details of the supposed vulnerability, a snippet that demonstrates the issue, and procedures to challenge their findings.
Receive a response from a Veracode Support email addressthat says, in part,
Are you saying our vuln db is not correct per your github source? If so, I can send it to our research team to ensure it looks good and if not, to update it.
As for snips of code, we do not provide that.
Reply, explaining that you find the report missing the details necessary to challenge it, but that yes, you expect it is incorrect.
Receive a response that this has been "shot up the chain" and that you will be hearing from them soon.
- Again, don't obsessively check your email or the StackOverflow question. But if you do happen to glance at StackOverflow, notice that while there are still no answers to it, there are enough upvotes to cover over half the cost of the bounty. Clearly you're not alone in wanting to know how to do this.
Receive an email from Veracode:
Thank you for your interest in Application Security and Veracode.
Do you have time next week to connect?
Also, to make sure you are aligned with the right rep, where is your company headquartered?
Respond that you're not a potential customer and explain again what you're looking for.
Add a comment to the StackOverflow to explain where the process has gotten to and expressing your frustration.
Watch another weekend go by without any way to address this concern.
Get involved in a somewhat interesting discussion about prototype pollution in the comments to the StackOverflow post.
Receive an actually helpful email from Veracode, sent by someone new, whose signature says he's a sales manager. The email will look like this:
Hi Scott, I asked my team to help out with your question, here was their response:
We have based this artifact from the information available in https://github.com/ramda/ramda/pull/3192. In the Pull Request, there is a POC (https://jsfiddle.net/3pomzw5g/2/) clearly demonstrating the prototype pollution vulnerability in the mapObjIndexed function. In the demo, the user object is modified via the
__proto__
property and is
considered a violation to the Integrity of the CIA triad. This has been reflected in our CVSS scoring for this vulnerability in our vuln db.There is also an unmerged fix for the vulnerability which has also been
included in our artifact (https://github.com/ramda/ramda/pull/3192/commits/774f767a10f37d1f844168cb7e6412ea6660112d )Please let me know if there is a dispute against the POC, and we can look further into this.
Try to avoid banging your head against the wall for too long when you realize that the issue you thought might have been raised by someone who'd seen the Veracode report was instead the source of that report.
Respond to this helpful person that yes you will have a dispute for this, and ask if you can be put directly in touch with the relevant Veracode people so there doesn't have to be a middleman.
Receive an email from this helpful person -- who needs a name, let's call him "Kevin" -- receive an email from Kevin adding to the email chain the research team. (I told you he was helpful!)
Respond to Kevin and the team with a brief note that you will spend some time to write up a response and get back to them soon.
Look again at the Veracode Report and note that the description has been changed to
ramda is vulnerable to prototype pollution. An attacker is able to inject and modify attributes of an object through the
mapObjIndexed
function via the proto property.but note also that it still contains no details, no snippets, no dispute process.
Receive a bounced-email notification because that research team's email is for internal Veracode use only.
Laugh because the only other option is to cry.
Tell Kevin what happened and make sure he's willing to remain as an intermediary. Again he's helpful and will agree right away.
Spend several hours writing up a detailed response, explaining what prototype pollution is and how the examples do not display this behavior. Post it ahead of time on the issue. (Remember the issue? This is a story about the issue.3) Ask those reading for suggestions before you send the email... mostly as a way to ensure you're not sending this in anger.
Go ahead and email it right away anyway; if you said something too angry you probably don't want to be talked out of it now, anyhow.
Note that the nonrefundable StackOverflow bounty has expired without a single answer being offered.
Twiddle your thumbs for a week, but meanwhile...
Receive a marketing email from Veracode, who has never sent you one before.
Note that Veracode has again updated the description to say
ramda allows object prototype manipulation. An attacker is able to inject and modify attributes of an object through the
mapObjIndexed
function via the proto property. However, due to ramda's design where object immutability is the default, the impact of this vulnerability is limited to the scope of the object instead of the underlying object prototype. Nonetheless, the possibility of object prototype manipulation as demonstrated in the proof-of-concept under References can potentially cause unexpected behaviors in the application. There are currently no known exploits.If that's not clear, a translation would be, "Hey, we reported this, and we don't want to back down, so we're going to say that even though the behavior we noted didn't actually happen, the behavior that's there is still, umm, err, somehow wrong."
Note that a fan of the library whose employer has a Veracode account has been able to glean more information from their reports. It turns out that their details are restricted to logged-in users, leaving it entirely unclear how they thing such vulnerabilities should be fixed.
Send a follow-up email to Kevin4 saying
I'm wondering if there is any response to this.
I see that the vulnerability report has been updated but not removed.
I still dispute the altered version of it. If this behavior is a true vulnerability, could you point me to the equivalent report on JavaScript'sObject.assign
, which, as demonstrated earlier, has the exact same issue as the function in question.My immediate goal is to see this report retracted. But I also want to point out the pain involved in this process, pain that I think Veracode could fix:
I am not a customer, but your customers are coming to me as Ramda's maintainer to fix a problem you've reported. That report really should have enough information in it to allow me to confirm the vulnerability reported. I've learned that such information is available to a logged- in customer. That doesn't help me or others in my position to find the information. Resorting to email and filtering it through your sales department, is a pretty horrible process. Could you alter your public reports to contain or point to a proof of concept of the vulnerability?
And could you further offer in the report some hint at a dispute process?
Receive an email from the still-helpful Kevin, which says
Thanks for the follow up [ ... ], I will continue to manage the communication with my team, at this time they are looking into the matter and it has been raised up to the highest levels.
Please reach back out to me if you don’t have a response within 72 hrs.
Thank you for your patience as we investigate the issue, this is a new process for me as well.
Laugh out loud at the notion that he thinks you're being patient.
Respond, apologizing to Kevin that he's caught in the middle, and read his good-natured reply.
Hear back from Kevin that your main objective has been met:
Hi Scott, I wanted to provide an update, my engineering team got back
to me with the following:“updating our DB to remove the report is the final outcome”
I have also asked for them to let me know about your question regarding the ability to contend findings and will relay that back once feedback is received.
Otherwise, I hope this satisfies your request and please let me know if any further action is needed from us at this time.
Respond gratefully to Kevin and note that you would still like to hear about how they're changing their processes.
Reply to your own email to apologize to Kevin for all the misspelling that happened when you try to type anything more than a short text on your mobile device.
Check with that helpful Ramda user with Veracode log-in abilities whether the site seems to be updated properly.
Reach out to that same user on Twitter when he hasn't responded in five minutes. It's not that you're anxious and want to put this behind you. Really it's not. You're not that kind of person.
Read that user's detailed response explaining that all is well.
Receive a follow-up from the Veracode Support email address telling you that
After much consideration we have decided to update our db to remove this report.
and that they're closing the issue.
Laugh about the fact that they are sending this after what seem likely the close of business for the week (7:00 PM your time on a Friday.)
Respond politely to say that you're grateful for the result, but that you would still like to see their dispute process modernized.
- Write a 2257-word answer5 to your own Stack Overflow question explaining in great detail the process you went through to resolve this issue.
And that's all it takes. So the next time you run into this, you can solve it too!
Update
(because you knew it couldn't be that easy!)
Day 61Receive an email from a new Veracode account executive which says
Thanks for your interest! Introducing myself as your point of contact at Veracode.
I'd welcome the chance to answer any questions you may have around Veracode's services and approach to the space.
Do you have a few minutes free to touch base? Please let me know a convenient time for you and I'll follow up accordingly.
Politely respond to that email suggesting a talk with Kevin and including a link to this list of steps.
1 This is standard behavior with Ramda issues, but it might be the main reason Veracode chose to report this.
2 Be careful not to get into an infinite loop. This recursion does not have a base case.
3 Hey, this was taking place around Thanksgiving. There had to be an Alice's Restaurant reference!
4 If you haven't yet found a Kevin, now would be a good time to insist that Veracode supply you with one.
5 Including footnotes.
QUESTION
I'm studying for the final exam for my introduction to C++ class. Our professor gave us this problem for practice:
...Explain why the code produces the following output:
120 200 16 0
ANSWER
Answered 2021-Dec-13 at 20:55It does not default to zero. The sample answer is wrong. Undefined behaviour is undefined; the value may be 0, it may be 100. Accessing it may cause a seg fault, or cause your computer to be formatted.
As to why it's not an error, it's because C++ is not required to do bounds checking on arrays. You could use a vector and use the at
function, which throws exceptions if you go outside the bounds, but arrays do not.
QUESTION
Why does the TypeScript compiler compile its optional chaining and null-coalescing operators, ?.
and ??
, to
ANSWER
Answered 2021-Nov-04 at 17:40You can find an authoritative answer in microsoft/TypeScript#16 (wow, an old one); it is specifically explained in this comment:
That's because of
document.all
[...], a quirk that gets special treatment in the language for backwards compatibility.
QUESTION
The new structural pattern matching feature in Python 3.10 is a very welcome feature. Is there a way to match inequalities using this statement? Prototype example:
...ANSWER
Answered 2021-Oct-29 at 00:10You can use guards:
Community Discussions, Code Snippets contain sources that include Stack Exchange Network
Vulnerabilities
No vulnerabilities reported
Install Answer
You can use Answer like any standard Java library. Please include the the jar files in your classpath. You can also use any IDE and you can run and debug the Answer component as you would do with any other Java program. Best practice is to use a build tool that supports dependency management such as Maven or Gradle. For Maven installation, please refer maven.apache.org. For Gradle installation, please refer gradle.org .
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