Prefix Sums - Problems, Code in C++ & Python
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- čas přidán 27. 06. 2023
- Prefix sums are the sums of the first K elements in an array. You can use them to quickly get the range sum and solve many other problems.
Range Sum - cses.fi/problemset/task/1646 or www.spoj.com/problems/CSUMQ/
Most Frequent - www.geeksforgeeks.org/queries...
Range Increase - www.hackerrank.com/challenges...
Subarray Sum Equals K - leetcode.com/problems/subarra...
Product - leetcode.com/problems/product...
CF article - codeforces.com/blog/entry/86420
I stream on Twitch - / errichto
2nd YT channel - / errichto2
Finally Errichto remembers,
That he has a CZcams channel😅
Finally he is here👏👏
no way!!! i was looking for this video last week, but i saw you had not uploaded in a long time… what a nice timing. welcome back, errichto!🎉🎉
Long time no see
happy that you are back 🙂
please make videos continuously ,it helps a lot
Is he back or is this not a repost?
Your lectures are fantastic, just the right amount of theoretical foundation and then a code dive-in, very well done, keep 'em coming Mr. Errichto!
Thanks for posting again! I really appreciate your videos. Your voice is calm and you're gifted in explaining it simply.
Greetings from Serbia.
Thank you for sharing this video! Your demonstration of the algorithm is amazing and straight forward with easy and hard problems, couldn't ask for a better video, thank you!
Errichto remembered his gmail password at last.
Glad you're back!!!
Thank you so much errichto, i was just looking for prefix/suffix sums for the last few days
We missed you so much
man im so happy you are back!
He is back!🎉
Thanks for the video! That type of content I find the most useful.
Thanks for the fantastic content!🌻
Finally you are back , i used to watch your videos when i eat food , finally again some great content . Love you man ....
Errichto is back! ❤️
Welcome back, glad to see u posting again
Glad to see you're back🤩
it's too time to see you again 🎉 I'm so happy ❤
The man himself is back at it again. Nice to have you back
Finally he is back after a long time 😊.
The legend's back!
Thank you for posting educational content, I am really grateful and sure that most people appreciate your content so much too.
please keep posting whenever you can, Thank you again!
Good to see u back😊
welcome bruh I'm happy to see you long time no see
Heyyy, very nice to see you back. I've learnt so many stuffs from you
I'm glad to see you again
happy to see that you are so back
the way you teach is perfect
He is backkk🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉❤❤❤❤
Welcome back man 🔥🤜
very happy to see you 😊❤
Thank you so muuch for all of this!!❤
Love your videos, was hoping you would post again soon :)
Legend comes🎉🎉🎉
The legend is back guys.❤❤❤❤❤❤
wow you are back! we missed you bro
I watched the binary search video and solved the problem you mentioned and more, and I will try to do that on this one again, and soon I will watch your dynamic programming series and solve them.
Thank you so much for your guidance and I hope you upload more because they are great and straightforward
If you are really interested in learning and have some free time. You should watch videos (previously recorded livestream) from Colin galen and Vivek gupta.
@@zanies6288 thank you so much for the recommendations, I really appreciate it and I will grind to solve and learn from them
the legend is back!
Keep on teach us erricto.🔥🔥
Finally,,,, After A Long Time❤
Excellent that you get back....¡¡¡¡¡¡
Very Helpful 👍🏾 Thank you sir
After long time!
The chosen one is back
Does this method work for suffix as well , where we use an array of size + 1? I ran into some errors
Pls make some more videos like this
Thank you
LET'S GOOOOOO! LOOK WHO'S HEREEE
The myth the man the legend.
Legends never die!🙂
He man thanks please be regular
YAY! ERRICHTO'S BACK!
Finally!!! I missed you😅
yeah same request : Please make more videos :)
Does anyone know what does:
*ios_base::sync_with_stdio(0);*
and
*cin.tie(0);*
mean?
In short, it makes cin/cout faster.
@@Errichto Is it actually any better than using scanf() and printf()? I've done some testing myself and found that cin/cout with the boost are faster but I've also found conflicting results on the internet. What's your experience with the two approaches
@@therealpancake7140 streams work with std::string, which makes them easier to use.
The best tutor
Hi Errichto. I was thinking that the prefix sum might not be the fastest for the string problem you mentioned in the video. I'm not quite sure yet because I don't feel like putting my idea in code to test it out. But thanks for the video anyways. It was really helpful
long time no see😂
I guess you will be uploading about algorithms now that's gonna be good
Top G is back 😌
What's the device that you are using to write in screen ?
Can you please answer.
Finally 😍😍😍
hello errichto i am currently on a search for a new laptop for CP and i wanted to know if you got any advices for choosing the right one?
After a long time.
raxmat bro
Good day Errichto! I have question. ( 10:00 )
at the 7 line :
s is string
s.length() = s.size() ?
Yeah same thing
Long time no see
Brother can you recommend me which book r best for DSA and competative programming. Ik practice is the key but please recommend me 😊
0:00 What is prefix sums?
4:31 Problem 1 : Static range sum queries
7:09 Problem 2 : Most common character in the substring
15:41 Problem 3 : Array manipulation 🤯
18:49 Summary
Will you be posting regularly?
In the last problem can we just put a if statement that adds x if i is in range l to r please correct me if i am wrong
And also as some one who just cp is a2oj a good resource or should i do something else also
If you do it separately for each of Q updates, the total time complexity is O(N*Q), which is too slow.
a2oj is ok as long as you solve problems that are difficult enough for you.
@@Errichto Thank you very much for your guidance 👍😊
Where did you set pref[0] = 0. Sorry if it is stupid to ask!
can i ask hint to hackerrank problem?
More videos please
Can you make a tutorial on problem solving. Like picking a harder problem and showing how to come up with some initial observations and ideas and work trough them to come up with a solution. A lot of times I just end up with a blank screen having difficulty even understanding what the problem is about.
I have hundreds of videos & streams about problem solving across my two channels. I rarely solve anything without explaining the thought process. If you want to see me struggle for hours, see any Atcoder Grand Contest streams like this one czcams.com/video/UJrzgjblMCM/video.html
@@Errichto This is it. Thank you.
✨💫
Hello kindly hear guys , this is stay-at -home mum , Could I ask for C++, which laptop or computer required? Which one is best ? Which application or soft need to install ( now we use Mac) - thank you so much for your assistance.
Good-hearted guys
@aisha9763, I don't use mac but hope this helps czcams.com/video/1E_kBSka_ec/video.htmlsi=H77gcqle7X-EVWOy
more videoss please
More edu videos please
first problem is basically what integral images are about.
Hi from Banja Luka
It's been a while 😭
I think erricto is the best programmer on earth without a *beard*
😶🌫️✨
Do you still do tutoring?
I do. You can find my email id in the "About" section on CZcams.
polska gurom
3 views 13 likes!
Eat burger
dawaj tyeraz po polsku
Can this comment get pinned?
Loved to see your content once again. Thanks you so much.