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How difficult are Codeforces tasks compared to IOI tasks?
By HappyLittlePony, 10 years ago, In English

Please tell me which problems from codeforces are best for preparation to IOI. Thank you and sorry for english :-)

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10 years ago, # |
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Try problems tagged 'data structures' or 'greedy'.

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10 years ago, # |
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Quite hard to compare. IOI would often focus more on data structures and clever algorithms rather than theory. So things like maximal matching,max-flow, solving systems of equations or almost any math at all, advanced geometry, etc.. are not needed for IOI, while you can get them quite often in Codeforces.

In my opinion the best way to practice for IOI is to solve past IOIs. If you have done that already though, and really want to use Codeforces to practice, I guess zxqfl's advice works best — "data structures" and "greedy" are the most common ones you'll get. Maybe "binary search" too :)

P.S.

Exact comparison between difficulty is also difficult to give. I can rarely solve Div1 D/E, but I've performed quite decently on the last two IOIs, just because the problem style is different.

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10 years ago, # |
  Vote: I like it +17 Vote: I do not like it

It varies from problem to problem. There is usually one easy, one medium and one hard problem in an IOI day. One of these problems can be replaced by a funny non-standard problem (e.g. Artclass in 2013). My opinion on difficulties of problems:

  • Easy problem: Div1 B for 100% points, or DIV1 A for ~50% points or quite easy bruteforce for ~15% points.
  • Medium problem: Div1 C for 100% points, or DIV1 B for ~50% points or quite easy bruteforce for ~15% points.
  • Hard problem: Div1 E for 100% points, or DIV1 C for ~60% points or something easier for less points.
  • Funny problem: Incomparable

DISCLAIMER: This opinion is based only on contests I participated in, which is not a very big set (3 IOIs and ~20 CF Div1 rounds).

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    5 years ago, # ^ |
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    My memory may not be what it used to be, but I'm pretty certain you took part in four IOIs, not three :)

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5 years ago, # |
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Answer to the original Question- I don't think that codeforces tasks difficulty can be directly compared with IOI task mainly because of two reasons, (1) Syllabus of IOI is limited but that's not the case in codeforces. (2) Codeforces task are made in such a way that everyone from novice coder to the world's best programmers can enjoy the contest hence overall difficulty varies alot.

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