Kotlin Heroes 6 Announcement

Hello, Codeforces!

First and foremost, we would like to say a massive thank you to everyone who entered and submitted their answers to the five Kotlin Heroes competitions which were held previously: Episode 1, Episode 2, Episode 3, Episode 4, and Episode 5: ICPC Round.

Ready to challenge yourself to do better? The Kotlin Heroes: Episode 6 competition will be hosted on the Codeforces platform on 09.03.2021 17:35 (Московское время). The contest will last 2 hours 30 minutes and will feature a set of problems from simple ones, designed to be solvable by anyone, to hard ones, to make it interesting for seasoned competitive programmers.

Prizes:

Top three winners will get prizes of $512, $256, and $128 respectively, top 50 will win a Kotlin Heroes t-shirt and an exclusive Kotlin sticker, competitors solving at least one problem will enter into a draw for one of 50 Kotlin Heroes t-shirts.

Registration is already open and available via the link. It will be available until the end of the round.

The round will again be held in accordance with a set of slightly modified ICPC rules:

The round is unrated.
The contest will have 9 problems of various levels of complexity.
You are only allowed to use Kotlin to solve these problems.
Participants are ranked according to the number of correctly solved problems. Ties are resolved based on the lowest total penalty time for all problems, which is computed as follows. For each solved problem, a penalty is set to the submission time of that problem (the time since the start of the contest). An extra penalty of 10 minutes is added for each failed submission on solved problems (i. e., if you never solve the problem, you will not be penalized for trying that problem). If two participants solved the same number of problems and scored the same penalty, then those of them who had previously made the last successful submission will be given an advantage in the distribution of prizes and gifts.

If you are still new to Kotlin we have prepared a tutorial on competitive programming in Kotlin and Kotlin Heroes: Practice 6, where you can try to solve a few simple problems in Kotlin. The practice round is available by the link.

We wish you luck and hope you enjoy Kotlin.

Invocation failed [COMPILATION_ERROR] Can't compile file: program.kt:5:30: error: calls to static methods in Java interfaces are prohibited in JVM target 1.6. Recompile with '-jvm-target 1.8' list.sortWith(Comparator.reverseOrder()) ^ Unable to find classes\programkt.class

Комментарии (33)

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vadimmm

4 года назад, # |

+29

Could you set -jvm-target kotlinc flag to 1.8+ (default is 1.6)?

Currently it's impossible to use static methods on interfaces (e.g. Comparator.reverseOrder()).

import java.util.Comparator

fun main() {
    val list = mutableListOf("Hello", "World")
    list.sortWith(Comparator.reverseOrder())
    println(list)
}

fails with

→ Ответить

MikeMirzayanov

4 года назад, # ^ |

+43

Thanks, I'll add it. But I prefer to do it after this round. I don't want to make changes to the settings before an important round.

+24

Done.

Jhin

I just have a question how can we change a char in a string in kotlin.. why its so wrong to do it like other languages
s="hold"; s[0]='g' that just doesn't work

rotavirus

the strings and a lot of other objects are immutable for simplicity. For example, it simplifies the creation of a substring — just put the pointers at the beginning and end of the substring

clyring

+11

If you need a mutable String-like object, try StringBuilder.

val s = StringBuilder("test");
s[0] = 'g';
s.append(s);
println(s); // gestgest

Abid29_retired

-56

can i use c++ in this contest??

gabaswillwinIOI2022

Yes of course this is Kotlin contest already

-30

i dont understand what r u trying to say??

Programmingsuks

i think its supposed to be sarcasm

Time_To_Night_Sky

-8

No you're only supposed to use Kotlin in this contest...

-64

but why man. problem solving should have no boundary. one should use whatever he is comfortable with.

nFlamel

+30

Because this is a contest made specially for Kotlin? It's the freedom of the setters to do whatever they want with their round, specially since this round is sponsored by JetBrains. If they want to promote Kotlin by making a Kotlin-only contest, they can do so.

SkyDreams

← Rev. 2 →

+34

You are only allowed to use Kotlin to solve these problems.

People blind or what ?

Venti_chai

+16

Note-People who won’t be able to participate in the contest, and want to solve the problems afterwards in their favorite languages can create mashups and do that.

lightseba

can we get a kotlin remix of this to listen to in contest? https://www.youtube.com/watch?v=WMiELYCfyJA

taran_1407

-18

Interesting Round.

Surprised with no graph problem (from A to G). Seems like writing graph template went to waste :P

quackdratic

+15

Fun experience, first round in Kotlin, feels fresh to use

huikang

Today I learnt to check whether I copied a template with val when I supposed to use var

Fawkes

-22

Tried Kotlin first time my clean solution to C.

Spoiler

private fun readLn() = readLine()!! // string line
private fun readStrings() = readLn().split(" ") // list of strings
private fun readInts() = readStrings().map { it.toInt() } // list of ints
    
fun main() {
    var t = readLn().toInt()
    for (tests in 0..t - 1) {
        var (n, x, y) = readInts()
        if(x>y) { 
            var temp=x;
            x=y;
            y=temp;
         };
         var ans=1000006;
         y=n-y+1;
         for( i in 0..n) {
             var k=n-i;
             var z1=0;
             var z2=0;
             if(i<=x) { 
                z1= x-1; 
             }
             else {
                z1 = minOf((i-x)+i-1,i+x-2);
             }
             if(k<=y) {
                 z2 = y-1;
             }
             else {
                z2 = minOf(2*k-y-1,k+y-2);
             }
             z1=maxOf(z1,z2);
             if(z1<ans) {
                 ans=z1;
             }
         }
        println(ans);
    }
}

jakubd

+10

Codeforces these days be like:

submitkotlin

When will the Random T-shirt winners will be announce?

qpwoeirut

+39

I recently saw an interesting blog which I think you might want to take a look at. In particular, the second link in the blog will probably be of interest. What are your thoughts on it?

PoIar_

+19

I guess it would be cool to detect plagiarism in this round as it's detected in regular rounds

Raftyy

All these accounts that are in these blog are created a few hours before the contest. It would be cool if jetbrains implies a new rule that you must have to participate at least one rated contest before to be eligible for the prize. Sad thing is these people are participating the contest just because of a t-shirt not for learning a new language.

Flash_98

+51

T-shirt winners????

ethicalfacts

+65

please give updates about random tshirt winners

MohamedAboOkail

When will the T-shirts winners be announced? It has been more than two days since the contest ended!

ibrahim_habib

+40

I think we should be patient.

Last time the winners list was announced one week after the contest.

We all should consider the amount of work that Mike and CodeForces staff are making to operate the website. Angry comments don't show such gratitude and may demotivate them.

We will eventually know the winners. A few days delay is not a big deal anyway because the prizes take much longer to be received.

songsinger

+18

That could be avoided by announcing approximate date of raffle. But I agree that asking the same question over and over again will change nothing.

SlimShady985

+48

When? ;-;

trendingaj

+27

Are the winners list out or any information on when it'll be out?

BF_OF_Priety

13 месяцев назад, # |

thanks for pushing me to learn kotlin