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Time Limit: 12 s Memory Limit: 1024 MB Total points: 100

#1824. 特殊环

Statistics

给定一个无自环、无重边的简单无向图。其中一些边被标记为 Special。

你的任务是寻找一个简单环,使得对于每一条 Special 边,该边要么属于这个环,要么其两个端点均不在环上。环不允许重复经过顶点。输出任意一个满足条件的解,若不存在,则报告无解。

输入格式

第一行包含三个整数 $n$ ($2 \le n \le 150$),$m$ ($1 \le m \le \frac{n(n-1)}{2}$) 和 $k$ ($1 \le k \le m$),其中 $n$ 是图中节点的数量,$m$ 是边的数量,$k$ 是 Special 边的数量。节点编号为 $1$ 到 $n$。

接下来的 $m$ 行,每行包含两个整数 $a$ 和 $b$ ($1 \le a < b \le n$),表示节点 $a$ 和 $b$ 之间的一条无向边。所有边各不相同。前 $k$ 条边为 Special 边。

输出格式

若存在满足条件的环,第一行输出一个整数,表示找到的环的长度。在接下来的行中,按环的顺序输出环上的顶点,每行一个。若不存在这样的环,则直接输出 $-1$。

样例

样例输入 1

8 10 3
1 2
4 5
7 8
2 3
3 4
1 4
5 6
6 7
5 8
3 8

样例输出 1

8
1
4
5
6
7
8
3
2

样例输入 2

4 6 3
1 2
1 3
1 4
2 3
3 4
2 4

样例输出 2

-1

Editorials

IDTypeStatusTitlePosted ByLast UpdatedActions
#600Editorial Open集训队作业 解题报告 by 陈翔乐Qingyu2026-01-18 16:21:19 Download

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