Does anyone know the live standings of IZhO 2022?
# | User | Rating |
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1 | tourist | 3993 |
2 | jiangly | 3743 |
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7 | awoo | 155 |
8 | TheScrasse | 154 |
9 | Dominater069 | 153 |
10 | nor | 152 |
Does anyone know the live standings of IZhO 2022?
Name |
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Today and tomorrow IZHO 2022
standings of day 1
Do you have the standings of Day 2?
standings of day 1 + day 2
How to solve A?
Given an array
a[1], ..., a[n]
. You can delete i-th element if2 * a[i] = a[i - 1] + a[i + 1]
. What's the minimal length of array after performing some operations?n <= 300000, 1 <= a[i] <= 10^9
Subtasks:
(14 points).
n <= 15
(13 points).
a[i] = i
(9 points).
a[i] <= 3
(17 points).
n <= 300
(18 points).
n <= 3000
(29 points). No additional constraints
+
DP on substrings
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 $$$d_n$$$.
Thank you very much
Do you have the other tasks too?
IZHO 2022 day 1 problem A really difficult for me
Can anyone tell me IZHO 2022 day 1 problem B and problem C
Does anyone know the standings of IZhO 2022 day 2?
standings of day1 + day 2