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Temotoloraia's blog

International Zhautykov Olympiad 2022
By Temotoloraia, history, 3 years ago, In English

Does anyone know the live standings of IZhO 2022?

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3 years ago, # |
  Vote: I like it +6 Vote: I do not like it

Today and tomorrow IZHO 2022

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3 years ago, # |
← Rev. 2   Vote: I like it +14 Vote: I do not like it

standings of day 1

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3 years ago, # |
← Rev. 6   Vote: I like it +15 Vote: I do not like it

How to solve A?

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    3 years ago, # ^ |
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    +

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    3 years ago, # ^ |
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    DP on substrings

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    3 years ago, # ^ |
    ← Rev. 2   Vote: I like it +56 Vote: I do not like it

    Let's look at the difference between adjacent elements.

    Assume that $$$b_i = a_{i+1}-a_i$$$, and now our task will be to remove equal neighbors, and put the doubled value instead.

    Now let's do some dynamic programming here, $$$dp_{l, r}$$$ — which determines whether we can remove a subarray $$$b_{l \dots r}$$$.

    The observation is that, for the fixed $$$l$$$, there at most $$$log_2(n)$$$ such $$$r$$$. Hence, for each $$$l$$$, we can just maintain a set that stores those rightborders. Try to come up with transitions by yourself.

    After calculating these $$$dp$$$ values, the problem can be solved with another dynamic programming. $$$d_i$$$ — minimal length of after performing operations on prefix $$$b_{1 \dots i}$$$. Answer to the problem will be $$$d_n$$$.

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    3 years ago, # ^ |
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    Do you have the other tasks too?

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3 years ago, # |
← Rev. 3   Vote: I like it +9 Vote: I do not like it

IZHO 2022 day 1 problem A really difficult for me

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3 years ago, # |
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Can anyone tell me IZHO 2022 day 1 problem B and problem C

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3 years ago, # |
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Does anyone know the standings of IZhO 2022 day 2?

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3 years ago, # |
  Vote: I like it +1 Vote: I do not like it

standings of day1 + day 2

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