Codeforces stream #2 - div1 A-B solving with explanation

Problem-solving of recent div1 A-B problems from Codeforces. Watch me if you want to practice Competitive Programming, algorithms or you want to learn for a coding interview. I share my thought process, explain everything, and mention similar problems that I know or techniques/algorithms that could be used too. Learn from me and grow your rating on Codeforces!
I'm known as Errichto. I compete in and organize programming competitions. I'm a finalist of ACM-ICPC, Topcoder Open, Facebook Hacker Cup and Google Code jam. I got a second place in Google Code Jam 2018.
What is Competitive Programming? en.wikipedia.org/wiki/Competi...
Follow me on Facebook: / errichto
Competitive Programming Discord: discordapp.com/invite/UzaURu7

Пікірлер: 44

  • @filipposoldati1472
    @filipposoldati14725 жыл бұрын

    2:29 Codeforces Round #517 - A: Cram Time 29:48 Codeforces Round #517 - B: Minimum path 1:30:30 Codeforces Round #124 - B: Infinite Maze 2:25:33 Technocup 2019 - Elimination Round 1 - E: Vasya and Good Sequences 3:31:56 Codeforces Round #272 (Div. 2) - D: Dreamoon and Sets Extra: 3:07:34 Improving suboptimal solution for 517B: Infinite Maze 3:26:47 Explanation for Educational Codeforces Round 3 - E: Minimum spanning tree for each edge

  • @Errichto

    @Errichto

    5 жыл бұрын

    Thank you a lot!

  • @arjuntomar215
    @arjuntomar2155 жыл бұрын

    great gesture of helping others, it helps a lot please continue these streaming as much as possible ,like me lots of people will love to see your streams very very useful

  • @shrad6611
    @shrad66114 жыл бұрын

    Please, guys, don't always compare him with tourist. He is best in his own way. Here he makes tutorial videos that help many people around the world. According to me he is best and I don't care about, he wins the competition or not but he is only one who helps us, tourist not.

  • @nihalk3935

    @nihalk3935

    3 жыл бұрын

    👍

  • @SuperSam4y0u
    @SuperSam4y0u5 жыл бұрын

    Thankyou so much Erichto! Your explanations were really helpful. I hope you keep making such videos and your channel keeps growing!

  • @guttsman
    @guttsman4 жыл бұрын

    This is helping me a lot because this kind of problem almost always have simple and/or smart tricks involved. Thanks for the time invested and hardwork! =D

  • @saikat93ify
    @saikat93ify5 жыл бұрын

    Appreciate your effort in making this video :)

  • @Errichto

    @Errichto

    5 жыл бұрын

    Cool, I'm glad you liked it :)

  • @rajavikramaditya6152
    @rajavikramaditya61525 жыл бұрын

    I always thot D.E and F were very tough, but you actually made me believe that they are not. Thank you.

  • @happyhappyguy5034

    @happyhappyguy5034

    4 жыл бұрын

    F is very tough

  • @sanjaysingh5007
    @sanjaysingh50075 жыл бұрын

    sir please make more videos on this Type of contest problems of codeforces they teach us alot..your efforts are awesome ...and are helping the students very much...

  • @vicfred2989
    @vicfred29895 жыл бұрын

    thanks for making this kind of videos, very appreciated

  • @dopamineaddict9690
    @dopamineaddict96905 жыл бұрын

    thanks a lot. the video is great and very educational. please keep making as many of these as possible.

  • @shrad6611
    @shrad66114 жыл бұрын

    Make more videos like this which have more explaination Love to watch your videos Big fan errichto

  • @user-du4pq7hh2x
    @user-du4pq7hh2x11 ай бұрын

    you are a genius! I wonder how that feels. Although I know not a stitch of what you do, I find it very interesting.

  • @sanjaysingh5007
    @sanjaysingh50075 жыл бұрын

    sir please make more videos on the algorithms TOPICS and concepts and please tell us about the books our resources to boost our CP skills. Your videos are Great...

  • @siddharthabiswas2147
    @siddharthabiswas21474 жыл бұрын

    the videos are really good ,thank you

  • @mizanurmazumder114
    @mizanurmazumder11410 ай бұрын

    Wow..! Its really a informative video

  • @akhilbinani6246
    @akhilbinani62464 жыл бұрын

    Codeforces Round #517 - B: Minimum path in the first part of the problem instead of DP, we can use Dijkstra`s algorithm to get the same matrix as of the DP matrix.

  • @tylerf1902
    @tylerf190211 ай бұрын

    very intersting stuff

  • @ankurdubey960
    @ankurdubey9605 жыл бұрын

    It's really helpful for me. Though best results at 1.25x.

  • @spamfriendly6489
    @spamfriendly64897 ай бұрын

    You are a god !

  • @igorbeliyaveski7600
    @igorbeliyaveski760011 ай бұрын

    WOW! Its cool maaaan

  • @magnuswootton6181
    @magnuswootton6181 Жыл бұрын

    YOU GET TO READ MORE NOTES IF THE NOTES TAKE LESS TIME TO READ. but u read the same amount of words...

  • @Haphazard1945
    @Haphazard194514 күн бұрын

    I've been writing software for years and haven't interviewed in about 10. This is never used on the job so why is it tested for during interviews? Wouldn't system design make much more sense?

  • @sandipsuryawanshi4788
    @sandipsuryawanshi478811 ай бұрын

    Good

  • @amhanafy
    @amhanafy5 жыл бұрын

    why at 16:00 at least one set has (k*(k+1))/4 ?? and what is k ? the number of remaining numbers from right?

  • @kamildebowski7003

    @kamildebowski7003

    5 жыл бұрын

    If you want to split A numbers into two groups, one group must have at least A/2 numbers. Here we have A=k*(k+1)/2. k is the number of remaining numbers on the left.

  • @amhanafy

    @amhanafy

    5 жыл бұрын

    ok now i know that if we want the remaining space between 2 sets k*(k+1)/4 but how we make sure that there's a space left so using the first while loop we make sure that the highest k here equal to i -1 can be splitted to 2 groups am i getting it right ?

  • @kamildebowski7003

    @kamildebowski7003

    5 жыл бұрын

    You're getting it right. And the proof was explained in the video.

  • @amhanafy

    @amhanafy

    5 жыл бұрын

    @@kamildebowski7003 thanks kamil your work is really appreciated looking forward for new live streams greetings from Egypt

  • @akaradet5387
    @akaradet538711 ай бұрын

    ดี

  • @ahmedshawky9845
    @ahmedshawky98455 жыл бұрын

    for the first problem how could we prove that you need to select numbers from right to left instead of left to right?

  • @Errichto

    @Errichto

    5 жыл бұрын

    I proved why taking from right to left worked. I also said some intuition why the opposite doesn't work: when you decide about some first numbers, you are left with big numbers that might not fit in either set/bag.

  • @imadudin2489
    @imadudin24895 жыл бұрын

    is this cutoff ?

  • @Errichto

    @Errichto

    5 жыл бұрын

    KZread takes a few hours to process a stream, and then it's available in full length, including chat on the side.

  • @imadudin2489

    @imadudin2489

    5 жыл бұрын

    okay, thank you. its full now

  • @darknessgamerz7505
    @darknessgamerz75056 ай бұрын

    nostalgia

  • @devidengo
    @devidengo8 ай бұрын

    Juluuiuuu 8:56 u