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A11685 | Minimal k-covering

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题目描述

You are given a bipartite graph $G=(U,V,E)$ , $U$ is the set of vertices of the first part, $V$ is the set of vertices of the second part and $E$ is the set of edges. There might be multiple edges.

Let's call some subset of its edges ![](/uploads/acgo/image/f3aa3c5a3809f680_db40202f431f.jpeg) $k$ -covering iff the graph ![](/uploads/luogu/CF976F/d49bf4cc25f3533c586c660e8b21a303cdd43d12_ad01921b7426.png) has each of its vertices incident to at least $k$ edges. Minimal $k$ -covering is such a $k$ -covering that the size of the subset ![](/uploads/acgo/image/f3aa3c5a3809f680_db40202f431f.jpeg) is minimal possible.

Your task is to find minimal $k$ -covering for each ![](/uploads/acgo/image/e1ba155dded241ac_9769d6f8e015.jpeg), where $minDegree$ is the minimal degree of any vertex in graph $G$ .

输入格式

The first line contains three integers $n_{1}$ , $n_{2}$ and $m$ ( $1<=n_{1},n_{2}<=2000$ , $0<=m<=2000$ ) — the number of vertices in the first part, the number of vertices in the second part and the number of edges, respectively.

The $i$ -th of the next $m$ lines contain two integers $u_{i}$ and $v_{i}$ ( $1<=u_{i}<=n_{1},1<=v_{i}<=n_{2}$ ) — the description of the $i$ -th edge, $u_{i}$ is the index of the vertex in the first part and $v_{i}$ is the index of the vertex in the second part.

输出格式

For each ![](/uploads/acgo/image/355a80bd19a7cf41_0863d864e41f.jpeg) print the subset of edges (minimal $k$ -covering) in separate line.

The first integer $cnt_{k}$ of the $k$ -th line is the number of edges in minimal $k$ -covering of the graph. Then $cnt_{k}$ integers follow — original indices of the edges which belong to the minimal $k$ -covering, these indices should be pairwise distinct. Edges are numbered $1$ through $m$ in order they are given in the input.

输入输出样例

输入 #1
3 3 7
1 2
2 3
1 3
3 2
3 3
2 1
2 1
输出 #1
0 
3 3 7 4 
6 1 3 6 7 4 5 
输入 #2
1 1 5
1 1
1 1
1 1
1 1
1 1
输出 #2
0 
1 5 
2 4 5 
3 3 4 5 
4 2 3 4 5 
5 1 2 3 4 5 
C++ 编辑器
输入
输出