Codeforces Round 576 (Div. 1)
C
Matching vs Independent Set
Codeforces
2000
原题
← BD →
翻译中…

You are given a graph with $3 \cdot n$ vertices and $m$ edges. You are to find a matching of $n$ edges, or an independent set of $n$ vertices.

翻译中…

A set of edges is called a matching if no two edges share an endpoint.

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A set of vertices is called an independent set if no two vertices are connected with an edge.

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Input

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The first line contains a single integer $T \ge 1$ — the number of graphs you need to process. The description of $T$ graphs follows.

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The first line of description of a single graph contains two integers $n$ and $m$, where $3 \cdot n$ is the number of vertices, and $m$ is the number of edges in the graph ($1 \leq n \leq 10^{5}$, $0 \leq m \leq 5 \cdot 10^{5}$).

翻译中…

Each of the next $m$ lines contains two integers $v_i$ and $u_i$ ($1 \leq v_i, u_i \leq 3 \cdot n$), meaning that there is an edge between vertices $v_i$ and $u_i$.

翻译中…

It is guaranteed that there are no self-loops and no multiple edges in the graph.

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It is guaranteed that the sum of all $n$ over all graphs in a single test does not exceed $10^{5}$, and the sum of all $m$ over all graphs in a single test does not exceed $5 \cdot 10^{5}$.

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Output

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Print your answer for each of the $T$ graphs. Output your answer for a single graph in the following format.

翻译中…

If you found a matching of size $n$, on the first line print "Matching" (without quotes), and on the second line print $n$ integers — the indices of the edges in the matching. The edges are numbered from $1$ to $m$ in the input order.

翻译中…

If you found an independent set of size $n$, on the first line print "IndSet" (without quotes), and on the second line print $n$ integers — the indices of the vertices in the independent set.

翻译中…

If there is no matching and no independent set of the specified size, print "Impossible" (without quotes).

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You can print edges and vertices in any order.

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If there are several solutions, print any. In particular, if there are both a matching of size $n$, and an independent set of size $n$, then you should print exactly one of such matchings or exactly one of such independent sets.

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Note

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The first two graphs are same, and there are both a matching of size 1 and an independent set of size 1. Any of these matchings and independent sets is a correct answer.

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The third graph does not have a matching of size 2, however, there is an independent set of size 2. Moreover, there is an independent set of size 5: 2 3 4 5 6. However such answer is not correct, because you are asked to find an independent set (or matching) of size exactly $n$.

翻译中…

The fourth graph does not have an independent set of size 2, but there is a matching of size 2.

翻译中…

样例

Input #1
4
1 2
1 3
1 2
1 2
1 3
1 2
2 5
1 2
3 1
1 4
5 1
1 6
2 15
1 2
1 3
1 4
1 5
1 6
2 3
2 4
2 5
2 6
3 4
3 5
3 6
4 5
4 6
5 6
Output #1
Matching
2
IndSet
1
IndSet
2 4
Matching
1 15
InputCopy OutputCopy
题目信息
题号
1198C
时间限制
1 s
内存限制
256 MB
标签
构造
图论
贪心
排序

题面与样例版权归 Codeforces 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。