Codeforces Round 680 (Div. 1, based on Moscow Team Olympiad)
B
Divide and Sum
Codeforces
1900
原题
← AC →
翻译中…

You are given an array $a$ of length $2n$. Consider a partition of array $a$ into two subsequences $p$ and $q$ of length $n$ each (each element of array $a$ should be in exactly one subsequence: either in $p$ or in $q$).

翻译中…

Let's sort $p$ in non-decreasing order, and $q$ in non-increasing order, we can denote the sorted versions by $x$ and $y$, respectively. Then the cost of a partition is defined as $f(p, q) = \sum_{i = 1}^n |x_i - y_i|$.

翻译中…

Find the sum of $f(p, q)$ over all correct partitions of array $a$. Since the answer might be too big, print its remainder modulo $998244353$.

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Input

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The first line contains a single integer $n$ ($1 \leq n \leq 150\,000$).

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The second line contains $2n$ integers $a_1, a_2, \ldots, a_{2n}$ ($1 \leq a_i \leq 10^9$) — elements of array $a$.

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Output

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Print one integer — the answer to the problem, modulo $998244353$.

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Note

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Two partitions of an array are considered different if the sets of indices of elements included in the subsequence $p$ are different.

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In the first example, there are two correct partitions of the array $a$:

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  1. $p = [1]$, $q = [4]$, then $x = [1]$, $y = [4]$, $f(p, q) = |1 - 4| = 3$;
  2. $p = [4]$, $q = [1]$, then $x = [4]$, $y = [1]$, $f(p, q) = |4 - 1| = 3$.
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In the second example, there are six valid partitions of the array $a$:

翻译中…
  1. $p = [2, 1]$, $q = [2, 1]$ (elements with indices $1$ and $2$ in the original array are selected in the subsequence $p$);
  2. $p = [2, 2]$, $q = [1, 1]$;
  3. $p = [2, 1]$, $q = [1, 2]$ (elements with indices $1$ and $4$ are selected in the subsequence $p$);
  4. $p = [1, 2]$, $q = [2, 1]$;
  5. $p = [1, 1]$, $q = [2, 2]$;
  6. $p = [2, 1]$, $q = [2, 1]$ (elements with indices $3$ and $4$ are selected in the subsequence $p$).
翻译中…

样例

Input #1
1
1 4
Output #1
6
InputCopy OutputCopy
Input #2
2
2 1 2 1
Output #2
12
InputCopy OutputCopy
Input #3
3
2 2 2 2 2 2
Output #3
0
InputCopy OutputCopy
Input #4
5
13 8 35 94 9284 34 54 69 123 846
Output #4
2588544
InputCopy OutputCopy
题目信息
题号
1444B
时间限制
2 s
内存限制
512 MB
标签
组合数学
数学
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