AtCoder Grand Contest 074
A
Communicate Topological Order
AtCoder
⌀ 2106
原题
←B →
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Problem Statement

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You are given a simple directed acyclic graph $G$ with $N$ vertices numbered $1$ to $N$. $G$ has $M$ edges, and the $i$-th edge is directed from vertex $x_i$ to vertex $y_i$.

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A permutation $P=(P_1,P_2,\ldots,P_N)$ of $(1,2,\ldots,N)$ that satisfies the following condition is called a special permutation:

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  • $P_{x_i} \lt P_{y_i}$ for all $i=1,2,\cdots,M$.
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You are given a special permutation $P$. Takahashi and Aoki will play a game using it. Takahashi knows the value of each term of $P$, but Aoki only knows that $P$ is a special permutation. Both of them know $G$. Takahashi selects some terms of $P$ and tells Aoki their positions and values. Find the minimum number of terms that Takahashi needs to tell Aoki so that Aoki can determine the values of all terms of $P$.

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Solve $T$ test cases per input.

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Constraints

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  • $1 \leq T \leq 10^4$
  • $1 \leq N \leq 2 \times 10^5$
  • $0 \leq M \leq 2 \times 10^5$
  • $1 \leq x_i,y_i \leq N$
  • The given graph $G$ is a simple directed acyclic graph.
  • $1 \leq P_i \leq N$
  • $P_1,P_2,\ldots,P_N$ are pairwise distinct.
  • $P_{x_i} \lt P_{y_i}$
  • The sum of $N$ over all test cases is at most $2 \times 10^5$.
  • The sum of $M$ over all test cases is at most $2 \times 10^5$.
  • All input values are integers.
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Input

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The input is given from Standard Input in the following format:

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T
case_1
case_2
\vdots
case_T

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Each case is given in the following format:

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N M
x_1 y_1
x_2 y_2
\vdots
x_M y_M
P_1 P_2 \ldots P_N

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Output

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Output $T$ lines in total. The $t$-th line should contain the answer for the $t$-th test case.

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样例

Input #1
3
5 4
3 4
4 1
3 1
5 2
5 4 1 2 3
4 0
4 2 1 3
10 15
6 2
8 5
4 9
7 10
3 7
5 6
8 9
3 5
5 2
8 2
3 9
5 9
10 2
3 2
7 4
8 9 2 6 4 5 3 1 10 7
Output #1
2
3
6
In the first case, if Takahashi tells that $P_1=5, \; P_4=2$, Aoki can determine all terms of $P$. Also, if Takahashi tells only one term of $P$, Aoki cannot determine all terms of $P$.
题目信息
题号
agc074_a
时间限制
2 s
内存限制
1024 MB

题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。