From c0ff31d6368c94582dba3513adc4814d0f6e2385 Mon Sep 17 00:00:00 2001 From: Matej Focko Date: Thu, 4 May 2023 23:55:11 +0200 Subject: [PATCH] pb071(pexam): add prep exam for seminar Signed-off-by: Matej Focko --- pb071/pexam/_category_.yaml | 6 + pb071/pexam/c-watching_cams.md | 209 +++++++++++++++++++++++++++++++++ 2 files changed, 215 insertions(+) create mode 100644 pb071/pexam/_category_.yaml create mode 100644 pb071/pexam/c-watching_cams.md diff --git a/pb071/pexam/_category_.yaml b/pb071/pexam/_category_.yaml new file mode 100644 index 0000000..3706c52 --- /dev/null +++ b/pb071/pexam/_category_.yaml @@ -0,0 +1,6 @@ +label: Practice Exams +position: 1 +link: + type: generated-index + description: | + Practice exams for training for the final exam. diff --git a/pb071/pexam/c-watching_cams.md b/pb071/pexam/c-watching_cams.md new file mode 100644 index 0000000..dae10fc --- /dev/null +++ b/pb071/pexam/c-watching_cams.md @@ -0,0 +1,209 @@ +--- +title: Practice exam C +description: | + Stalking cars… +--- + +# Watching Cams + +:::caution Exam environment + +* During the exam you will be provided with a barebone _exam session_ on the + _faculty computers_. +* In browser you are only allowed to have the following tabs open: + * [C documentation](https://en.cppreference.com) + * page containing the assignment +* You **are not** allowed to use your own source code, e.g. prepared beforehand + or from the seminars. +* You have **5 minutes** to read through the assignment and ask any follow-up + questions should be there something unclear. +* You have **60 minutes** to work on the assignment, afterward your work will be + discussed with your seminar tutor. + +::: + +Your task is to write a program `cams` that will be processing input from the +cams that are capable of identifying license plates on the cars and then +evaluate the queries on the given data. Your contributions to the society are +very much appreciated and may (or may not) be used for (each or none) of the +following purposes: + +* stalking people leaving and coming back home, +* retroactively making people pay for the parking, +* providing evidence of people speeding on highways, +* tracking people that don't pay tolls, or +* convict employees leaving the work prematurely. + +## Format of the input files + +Input for your program consists of the data from the cameras and queries. You +will be **always** given the data from the cameras as a path to a file, whereas +user should be able to specify `-` (i.e. `stdin`) as the path to queries. + +:::tip Validation of data + +For the sake of simplicity (and partially relieving the time pressure), you +**are not** required to validate the dates you are given on the input (e.g. leap +years, days in months, etc.). + +This is caused by the fact that you will be given just a timestamp that you +**don't** need to process in any (other than suggested ways for debugging). + +::: + +### Data from the cameras + +Each “scan” (i.e. reading) of the cameras consists of the following data: + +* _camera ID_: non-negative integer identifying a camera +* _plate_: string of unknown length that can consist of any characters apart + from whitespace +* _timestamp_: timedate of the scan as an unsigned integer (represented as a + UNIX time) + + :::tip + + When programming on UN\*X(-like) systems, you can assume that the `time_t` + structure from the system header `time.h` **is** the `unsigned int` that you + are provided in the input file. + + ::: + +And they are compiled into one reading such as: + + camera_ID: plate timestamp + +There should be always **at least one** space in between each part of the +reading. Reading are separated by the commas, which may, but don't have to, be +accompanied by whitespace around. + +#### Examples + +Few examples of the data from the cameras follow + +``` +10: ABC-12-34 1664608712, 289: XYZ-98-76 1665416417, +25: ABC-12-34 1633078256 , 42: TryToCatchMe 1671602419, +11: EL9-987 1679541338 ,2 : Foo-666 1683170082,42: YourMum 1683170082, +42: TryToCatchMe 1671602419 , 1234: TryToCatchMe 1671602419, +19: ABC-12-34 1664659649, 69:YouShould-not-pLaCe-4ny-expectations%on^the(input 1680307994, +9 : 9B9-161 1665416417 , 10: 1a1-999 1671602419,1:lmao 1633078256 +``` + +### Queries + +Querying the processed data is done by providing a license plate. You can expect +that the license plates are separated by `\n` (newline, also known as +_ňjůlajn_) **with no other whitespace around**. + +#### Examples + +Few examples of the queries follow + + ABC-12-34 + TryToCatchMe + Foo-666 + EL9-987 + + +## Format of the output + +:::info + +All the examples above consider using data from the first example of the input. + +::: + +You may encounter these situations (and handle them in the following order): +1. License plate was not found + + ``` + 404-not-found + *** 404-not-found *** + License plate was not found. + ``` +1. License plate was found + + In such case, you are expected to print out the dates and cameras that has + captured the license plate. + + If there are multiple scans present and the timespan (i.e. time difference + between the scans is bigger than 60 minutes, you are to separate them by a + newline). + + ``` + ABC-12-34 + *** ABC-12-34 *** + 25: Fri Oct 1 10:50:56 2021 + 10: Sat Oct 1 09:18:32 2022 + + 19: Sat Oct 1 23:27:29 2022 + ``` + + :::tip + + Since you are given the timestamp in a `time_t` compatible type on UN\*X, you + can safely use `ctime` for printing the timestamp as a _human readable_ time + when outputting the date and time. + + ::: + + +:::tip + +For a better readability you can include one more newline after the last line +of the output. + +::: + +## Example usage + +You can also have a look at example usage of your program. We can run your +program from the shell like + + $ ./cams example_1.txt - + +And then provide the queries, since we specified `-` as the file for the queries + + > ABC-12-34 + *** ABC-12-34 *** + 25: Fri Oct 1 10:50:56 2021 + 10: Sat Oct 1 09:18:32 2022 + + 19: Sat Oct 1 23:27:29 2022 + + > NonExistentLicensePlate + *** NonExistentLicensePlate *** + License plate was not found. + + > EL9-987 + *** EL9-987 *** + 11: Thu Mar 23 04:15:38 2023 + + > TryToCatchMe + *** TryToCatchMe *** + 42: Wed Dec 21 07:00:19 2022 + 42: Wed Dec 21 07:00:19 2022 + 1234: Wed Dec 21 07:00:19 2022 + +:::info + +Lines prefixed with `> ` in the example above represent the user input. + +::: + +## Requirements and notes + +* Define **structures** (and **enumerations**, if applicable) for the parsed + information from the files. +* For keeping the “records”, use some **dynamic** data structure. + * Don't forget to consider pros and cons of using _specific_ data structures + before going through implementing. +* You **are not required** to produce 1:1 output to the provided examples, they + are just a hint to not waste your time tinkering with a user experience. +* If any of the operations on the input files should fail, + **you are expected to** handle the situation _accordingly_. +* Failures of any other common functions (e.g. functions used for memory + management) should be handled in **the same way** as they were in the + homeworks and seminars. +* Your program **must free** all the resources before exiting.