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3222：Edge Pairing
Special Judge 特殊评判题目描述
Given a simple connected undirected graph with n vertices and m edges, where m is even, your task is to find a pairing of the edges such that each pair of edges shares a vertex.
输入解释
The input contains exactly one test cases. On the first line of the test case there are two integers n and m (3 ≤ n ≤ 20,000, 2 ≤ m ≤ 100,000, m is even) which indicate the size of the graph. Next come m lines each with a pair of integers a and b representing an edge (a, b). The vertices are numbered 1 through n.
输出解释
If a pairing exists, output it in m⁄2 lines. Each line contains three integers a, b and c in this order, indicating that the edges (a, b) and (b, c) are paired together. If no pairing exists, just output “NO” and nothing else.
输入样例
7 10 1 2 1 3 2 4 3 4 4 5 4 6 5 7 6 7 2 5 3 6
输出样例
1 2 4 1 3 4 4 5 2 4 6 3 5 7 6
提示
Illustration of the sample test case:
最后修改于 2020-10-29T06:56:10+00:00 由爬虫自动更新
共提交 0 次
通过率 --%
| 时间上限 | 内存上限 |
| 3000 | 131072 |