AtCoder Grand Contest 067
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Problem Statement
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You are given a simple undirected graph $G$ with $N$ vertices numbered $1$ to $N$. $G$ has $M$ edges and the $i$-th edge connects vertices $A_i$ and $B_i$.
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Check if $G$ satisfies the following condition:
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- For every subset
$X$of the vertex set$\{1,2,\cdots,N\}$, there exists a subset$Y$of$X$such that$|Y|\ge \frac{|X|}{2}$and$Y$forms a clique.
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You have $T$ testcases to solve.
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Constraints
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$1\le T \le 10^3$$1\le N \le 10^5$$0 \le M \le 10^6$$1 \le A_i,B_i \le N$- The given graph doesn't contain self-loops or multiple edges.
- The sum of
$N$across the test cases in a single input is at most$10^5$. - The sum of
$M$across the test cases in a single input is at most$10^6$. - All input values 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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T
case_1
case_2
\vdots
case_T
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Each test case is given in the following format:
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N M
A_1 B_1
A_2 B_2
\vdots
A_M B_M
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Output
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For each test case, if $G$ satisfies the condition, print Yes, and otherwise print No.
In printing Yes or No, you can output each letter in any case (upper or lower).
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样例
Input #1
4
3 3
1 2
1 3
2 3
3 2
1 2
1 3
3 1
1 2
3 0
Output #1
Yes
Yes
Yes
No
For the $1$-st test case, $G$ satisfies the condition. In this case, every subset $X$ is a clique, so we can just let $Y=X$.
For the $2$-nd test case, $G$ satisfies the condition. For example, for $X=\{2,3\}$, we can let $Y=\{2\}$.
For the $4$-th test case, $G$ doesn't satisfy the condition. If we let $X=\{1,2,3\}$, no subset $Y$ of $X$ satisfies the condition.
题目信息
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。