This olympiad is for students from 8th to 11th grades of Russian school.

"А" тоже элементарная. Простой способ: расписать if-ы для каждой цифры.

Разве это корректно — обсуждать еще не закончившийся контест?

Решение за O(NlogN). Делаем бинпоиск по количеству взятых велосипедов. Пусть сейчас мы хотим проверить, можно ли взять X велосипедов.

Считаем Cost — количество денег, необходимое для покупки X самых дешёвых велосипедов. Потом берём X самых богатых детей, считаем, сколько их наличных денег мы можем максимально истратить, пусть это количество равно Cash. Проверяем, что Cash + Budget ≥ Cost, тогда для того, чтобы набрать X велосипедов нам нужно max(0, Cost - Budget) личных денег.

t = t + s[i - 1] + s[i - 1];

Вот эта строчка работает за длину строки.

Но 8 претест == 8 тест, как так?

• first make n equals to m : if (n>m) take only the richest m boys, if (n<m) take only the cheapest n prices.
• use binary search to search r , store the total amount spent by boys s everytime you check the condition in binary search. The answer for s is the last true condition in binary search check (that is, the largest possible r we found).
• To check the condition in binary search, check it greedily : let's say you want to check for the answer X, then choose X richest boys and X cheapest bikes. Pair them respectively and see if it's possible for those X boys to buy those X bikes.

Sorry for my English :)

t+=s[0];
t+=s[1];

t contains 2 chars now, but in answer there is only one (s[0]).

s[1] does not exist at all, actually, so that I wonder why it is not runtime error :)

Same thing happened to me! My Submission fails on test 15:

Input
zz
Output
zz
Answer
zz
Checker comment
wrong answer Result is not a subsequence: 'zz' not in 'zz'

it maybe due to this piece of code

ans += s[0];
ans += s[1];

u are adding 2 characters to ans, when there is only one character in input.

EDIT: but what i dont know is why this resulted in Wrong Answer rather than Runtime Error. also, i agree with you that the Checker Log is contradicting itself!

Тоже интересно. Я пытался двумя указателями, но ошибку в коде не нашел.

:)

This part is causing the problem : ~~~~~ if(s[0] == s[1] && s[1] == s[2]){ index = 2; }else{ s1[2] = s[2]; index = 3; }

~~~~~

For the given case "zz", s[2] does not exist, thereby the control goes to the else condition and index is set to 3. So you are actually printing extra space along with your answer, which is invalid.

yes, my bad ... :( it is '\0' and shouldn't be printed. So the reason which I gave you, regarding your control going to the else condition is correct, whereas you are printing '\0'. Thanks for correcting me mathlover :)

Поговори мне о баллах за С.

It's weird that I and several people got the same output for test 20. Is there something tricky in the problem that we possibly misunderstood?

See Codeforces contests' format, you'll figure out.

Ok.Null charachter was the issue. But i want to know.Why did WA came on 52nd test case when i did not put null charachter in the Output string and printed using %s.

but the E... only one person ac it in the last minute...

I'm Master with rating 1408 :) I think they rollback rating because of some problems related to problem "E"

It seems the rating change for this match has been reverted due to an issue of problem E,but they forgot to update the handle colour.....

Are you happy now?

PAG, ruban