No.3437 [Cherry 8th Tune C] Silhouette
Problem Visual
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Problem Statement
There are $3$ points $A, B, C$ in $xyz$ space. The coordinates of $A, B, C$ are $(a_x, a_y, a_z), (b_x, b_y, b_z), (c_x, c_y, c_z)$, respectively.
Let $S$ be the area of the shadow of triangle $ABC$ on the $xy$ plane cast by a point light source located at coordinates $(l_x, l_y, l_z)$. If the shadow is a line segment or a point, let $S = 0$.
Find $S \pmod{998244353}$.
Solve $T$ test cases.
Notes
Under the constraints of this problem, it can be proved that there exists a pair of integers $(\alpha, \beta)$ satisfying the following.
- $\beta$ is not a multiple of $998244353$.
- $\beta \times S = \alpha$.
For a pair of integers $(\alpha, \beta)$ satisfying this condition, there exists exactly one integer $\gamma$ satisfying $$\beta \times \gamma \equiv \alpha \pmod{998244353}$$ that is at least $0$ and less than $998244353$. Using this integer $\gamma$, we define $S \pmod{998244353} := \gamma$.
Note that although there can be many pairs of integers $(\alpha, \beta)$ satisfying the condition, it can be proved that $\gamma$ does not depend on the choice of $\alpha, \beta$ and is determined only by $E$.
Constraints
- $1 \leq T \leq 10^5$.
- Constraints for each test case
- $\lvert a_x \rvert \leq 10^6$
- $\lvert b_x \rvert \leq 10^6$
- $\lvert c_x \rvert \leq 10^6$
- $\lvert a_y \rvert \leq 10^6$
- $\lvert b_y \rvert \leq 10^6$
- $\lvert c_y \rvert \leq 10^6$
- $1 \leq a_z \leq 10^6$
- $1 \leq b_z \leq 10^6$
- $1 \leq c_z \leq 10^6$
- $\lvert l_x \rvert \leq 10^6$.
- $\lvert l_y \rvert \leq 10^6$.
- $1 \leq l_z \leq 10^6$.
- $\max(a_z, b_z, c_z) \leq l_z$
- $A, B, C$ are not $3$ collinear points.
- All input values are integers.
Input
$T$
${\rm Testcase}_1$
$\vdots$
${\rm Testcase}_T$
Each test case is given in the following format.
$a_x$ $a_y$ $a_z$ $b_x$ $b_y$ $b_z$ $c_x$ $c_y$ $c_z$ $l_x$ $l_y$ $l_z$
Output
The output consists of $T$ lines. On line $t~(1 \leq t\leq T)$, print the answer for test case $t$.
Do not forget the newline at the end as well.
Sample
Sample 1
Input
3 9 -2 3 3 0 4 4 5 2 1 2 5 3 -1 3 0 9 4 7 -3 9 13 -6 18 8 29 2001 8 18 2004 2 17 2003 4 6 4646
Output
75 0 917747442
- [Test case $1$]
The shadow of triangle $P_1 P_2 P_3$ on the $xy$ plane is the triangle with the $3$ vertices $(6, 7), (21, -8), (11, -8)$. The area $S$ of this shadow triangle is $S = 75$.
- [Test case $2$]
The shadow of triangle $P_1 P_2 P_3$ on the $xy$ plane is the line segment with endpoints $(1, 0), \left(-\dfrac{26}{7}, \dfrac{93}{7} \right)$. Therefore, $S = 0$.
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Kazun