$ DrinkGrass! $ Unexpectedly exam? ? ? Late $ 10min $
Before
T1
greedy?
T2
law?
T3
cancer?
During
T1
2 2 4 7 1 5 3 1 4 4 6 3 5
It is greedy,
After as long as one "waste" less,
Front left and more to follow.
Thus $ \ Theta (TN \ log N) $ seems to be over $ N = 1e5 $
T2
$ O (N \ log \ mod) $ pretreatment, $ \ Theta (T) $ EMM to answer ...... $ $
I'm mad?
probably……
Nature ($ YY $):
$ (N!) ^ 2 = ((n-1)!) ^ 2 * n ^ 2 $ apparent.
To deal with the main denominator.
I think, and kind Hui triangle relationship ......
$$C_n^i=C_{n-1}^i+C_{n-1}^{i-1}$$
$$(C_n^i)^2=(C_{n-1}^i)^2+(C_{n-1}^{i-1})^2+2 \times C_{n-1}^{i} \times C_{n-1}^{i-1}$$
So to maintain two things, one is the sum of squares, it is a neighbor and key product.
The last term is twice the product and neighbor and with twice the square.
So transferred from the square
Drink Grass $ $
O items and how to transfer product?
Continue to play table ......
$$emm\\[50ex]
\vdots\\[50ex]
$$
$ans=C_n^0 \times C_n^n+C_n^1 \times C_n^{n-1}+\cdots$
Thus modeling, to take two sets of size n-$ $ a, which is selected from a a $ I $, $ another which is selected from a Ni $.
If that is the collection of $ 2n $ selected $ n $ th? ? ?
$ Ans big, sometimes small $ ......
fan……
Violence wrong (ruin)
Finally play coming!
T3
I remember I read horse-drawn vehicles ...... forget =. =
Put the cart before the horse on the team $ qwq $ Mozambique
But I can only fight violence spicy (will not hit $ QAQ $).
Try $ S ^ 2 $ prefix and pre-treatment?
The old feeling of "data structure" is fool me ~~
Try to make a two-way $ hash $?
Minute jig?
After
|
28
|
Miemeng | 0
03:14:34
|
100
03:14:34
|
20
03:14:35
|
120
03:14:35
|
to sum up:
Body of water ......
I wrote T1 is a positive solution ...... but for some reason metaphysics (...... accidentally deleted the Sort) WA0 the
T2 is a persimmon: $ C_ {2n} ^ {n} $ is positive Solutions
T3 is really not scale data, but the real data structures: arrays! (Actually $ dp $)