AtCoder Grand Contest 036
C
GP 2
AtCoder
⌀ 2357
原题
← BD →
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Problem Statement

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We have a sequence of $N$ integers: $x=(x_0,x_1,\cdots,x_{N-1})$. Initially, $x_i=0$ for each $i$ ($0 \leq i \leq N-1$).

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Snuke will perform the following operation exactly $M$ times:

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  • Choose two distinct indices $i, j$ ($0 \leq i,j \leq N-1,\ i \neq j$). Then, replace $x_i$ with $x_i+2$ and $x_j$ with $x_j+1$.
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Find the number of different sequences that can result after $M$ operations. Since it can be enormous, compute the count modulo $998244353$.

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Constraints

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  • $2 \leq N \leq 10^6$
  • $1 \leq M \leq 5 \times 10^5$
  • All values in input are integers.
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Input

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Input is given from Standard Input in the following format:

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N M

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Output

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Print the number of different sequences that can result after $M$ operations, modulo $998244353$.

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样例

Input #1
2 2
Output #1
3
After two operations, there are three possible outcomes: - $x=(2,4)$ - $x=(3,3)$ - $x=(4,2)$ For example, $x=(3,3)$ can result after the following sequence of operations: - First, choose $i=0,j=1$, changing $x$ from $(0,0)$ to $(2,1)$. - Second, choose $i=1,j=0$, changing $x$ from $(2,1)$ to $(3,3)$.
Input #2
3 2
Output #2
19
Input #3
10 10
Output #3
211428932
Input #4
100000 50000
Output #4
3463133
题目信息
题号
agc036_c
时间限制
2 s
内存限制
1024 MB

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